.
Since ".Com" is purely alphabet, you do need to be in alphabet mode. But instead of using "Control+Blank" or whatever combinaton of two keys, you can simply pre-program, depending on the software you use, a single key to do that in toggle mode. Which of two states is the current mode is typically shown in the video display. So one can program, say F2 (or F12 or whatever key you fancy), to do that. Press once it is in Chinese input mode, press it again it switches to English input mode. Press it again, it switches back to Chinese input mode. Of course it is a bit inconvenient. But then one can use clipboard function to past ".Com" or whatever alphabetic string, if that occurs often in a particular document.
The combination of both Chinese and English in a document is far less common than all-Chinese documents.
The quality of the input software is very important as good ones will keep track of your past typing history to guess the most likely meaning of any abbreviated letters.
For example, the full PinYin for UnitedStates or UnitedStatesOfAmerica is MeiGuo, but because this is such a common term, typing "mg" will immediately show the corresponding Chinese character for MeiGuo, i.e. 美国， as your very first choice, which is what you want in most cases. So you can save keystrokes and speed up that way.
As another example, full PinYin for China is ZhongGuo, but if you merely type "zg" or "zhg", the first displayed term is 中国， which is exactly the Chinese characters for China. Note that both 美国 and 中国 have the second character identical because that character 国 means "nation" or "country". The concept of taxonomy is very important. Just like Chinese bird names will end with the word 鸟 which is the Chinese character for "bird". There is really not much grammar in Chinese compared to English because the placement of a Chinese character as well as its meaning largely determine whether it is adjective or noun. You don't have to learn additional words or characters to distinguish the various forms, as you do in English.
Another interesting aspect of such AI-assisted input is that longer terms are in fact faster to input because the unique abbreviation is also longer and therefore less likely to cause ambiguity or confusion. For example, if I type "zh" to mean 中, the software is not too sure as "zh" can mean other equally likely words. But if I type "zhg" or "zg"， the AI is now able to narrow it down a lot more so that it will in fact typically show "中国" as its top guess of what I mean, which is in fact correct. Likewise, if I type ''zgrm" the software is even more certain that I mean "Zhong/Zong Guo Ren Min/Ming" or "中国人民" (meaning "Chinese People"). So it often happens that a long phrase in Chinese characters can be typed quicker using initial letters because the combination of extra letters allows the software to narrow it down to the right combination of Chinese characters with greater accuracy and confidence. In other words, a string of gibberish Chinese characters will take many more key strokes to input since they do not form meaningful Chinese phrase groups. Whereas meaningful Chinese terms and phrases will allow abbreviations and therefore save a lot of key strokes and be more accurate to boot.
Nor is there singular or plural versions for a word. If you want to show it is plural, you add 们 to signify that.
For example 我 is the same character you use whether you use it to mean "I" or "Me". To mean "We" or "Us", you simply use 我们.
It is special considerations such as the above that enable experienced PinYin typists to input Chinese characters much faster than their English equivalents.
For example, full PinYin for "My Country" is "WoGuo", but as the two character term happens regularly, typing "wg" will be interpreted as 我国 and 我国 will be offered as the best guess, and typically correct. Contrast typing "My Country" and typing "wg" to mean the same in both languages, and it should be obvious which is quicker. Also note that 我 (which normally means "I" or "Me" or "Self") when placed before the character 国 becomes a qualifier or adjective equivalent to "My". Likewise 我家 means "My home/family" since 家 is a character meaning home or family. I digress a little to show the simplicity of Chinese grammar which obviates a lot of variations in verb tense, gender, plurality, prepositions, etc. by simply relying on straightforward and existing characters as qualifiers and their placement/positioning relative to the characters to be qualified.
In fact you can write Chinese in any direction, be it left to right or right to left, horizontally or vertically, up or down, in any curvilinear, spiral, circular or zigzag pattern. The native reader will have no difficulty in immediately figuring out the right (i.e. correct) and meaningful direction. One can choose a conventional format, but it is not necessary for full comprehension. The language is very compact, lean or laconic, and information-dense. As a result, knowing just a modest number of Chinese characters will easily go several times further in communication and comprehension than knowing the same number of English words.
Hope this makes it quite clear why the usage of Chinese characters is far more preferred over PinYin or English words in China, for reasons quite aside from cultural roots. This is also why Chinese IDNs present significant advantages for native users of the language.
(now typing in pinyin)
