First question:

The subject and subordinate are generally used in conditional adverbial clauses, and conditional sentences are not guided by that.

Unless your that clause refers to objective truth, famous sayings or schedules of planes, cars, etc.

Second question: The difference between look see watch

< p>1) Look means "to see", it is an intransitive verb, emphasizing the action of looking. If you want to see something, use look at.

Please look at the blackboard. Please look at the blackboard. (That is, making the action of "looking")

In addition, look can also be used alone to attract the listener's attention. It is usually used with the present continuous tense:

Look! There is a plane flying in the sky. Look! There is an airplane flying in the sky.

2) See means "to see" and is a transitive verb, emphasizing the result of the action.

Can you see the words on the blackboard? Can you see the words on the blackboard?

The difference between look and see can be understood from this sentence:

I looked at the blackboard, but saw nothing. I looked at the blackboard, but saw nothing.

3) Watch means "watch", it is a transitive verb, usually used for movies, TV shows, competitions, etc.

I like watching films.

But "watching a movie" can be said to watch a film, or see a film