Learn 正在 + 动词 and A + 还是 + B？ through Before Going to Work.
Examples
用电脑。
To use a computer.
Examples
今天天气非常好。
The weather is very nice today.
这是非常时期。
This is an extraordinary period.
Examples
他很快就会回来。
He will be back very soon.
Examples
如果你去，我就去。
If you go, then I'll go.
他就来了。
He will come right away.
Examples
我每天八点上班。
I go to work at eight o'clock every day.
Examples
我正在准备晚饭。
I am preparing dinner.
你准备好了吗？
Are you ready?
Examples
请坐。
Please sit down.
坐车。
to take a vehicle
S + 正在 + V (chỉ hành động đang diễn ra)Use 正在 to express an action happening at the moment of speaking. It works like 'be ...-ing' in English.
他正在准备饭。
He is getting the meal ready.
我正在从外边回来。
I’m on my way back from outside.
A + 还是 + B？(lựa chọn)Use 还是 to present a choice or comparison, usually in a question. 还是 means 'or'.
你记得这些，还是忘了？
Do you remember these, or have you forgotten?
你喝水还是喝茶？
Do you want water or tea?
S + 还 / 也 + 动词、形容词还 (hái) means "still / in addition"; 也 (yě) means "also". Both go before the verb or adjective, never at the end.
我还有一些事。
I still have a few things to do.
他也回来了。
He came back too.
Xiao Lin and Xiao Nan are roommates. One morning, Xiao Nan is getting his things ready for work.
早上好！你正在准备什么？
Good morning! What are you getting ready?
我在准备去上班。这些是文件，还有我的电脑。
I'm getting ready to go to work. These are documents, and my computer too.
你记得从家里坐几路汽车吗？
Do you remember which bus number to take from home?
记得，最好的还是三路车。你呢？你还是开车去上班吗？
I remember — bus number 3 is still the best. And you? Do you still drive to work?
今天我不开车，我坐汽车去。
Today I'm not driving — I'll take the bus.
非常好！坐汽车也很快。你准备什么时候回来？
Great! The bus is quick too. When are you planning to come back?
大概下午五点就回来了。
Around five in the afternoon I'll be back.