主将if从现
即主语是将来时，从句是一般现在时
无论if在句首或是句中，紧跟着if后的就是从句。
例句：I will travel if I find the treasure.
If the rains heavily this afternoon. Uncil Tom will stay at home.
Don't be worried . He will call you if he arrives in New York.
when 当......时候
when前主句，when后从句
enough adj.足够的
adv.足够
形e 名
enough在名词前 在形容词，副词后
He has enough time to learn Chinese and he learns it well enough.
Can you see the words on the blackboard clearly enough?
