根据要求完成句子1.He doesn't know when he will start tomorrow.(改为简单句

1.He doesn't know when he will start tomorrow.(改为简单句）
He doesn't know _when___ ___to__ __start___ tomorrow.
2.What will happen if it rains tomorrow?(改为同义句）
__What___ ___if__ it rains tomorrow?
3.Tomorrow will be fine .We will go climbing.(用if将两句合成一句）
We _will___ ___go__ climbing _if____ ___it__ ___is__ fine tomorrow.

1.when to start
2.what if
3.will go if it is