完成句子。（每空1分，共10分）
He improves his English by joining an English club. (对划线部分提问）
________  ________ he improve his English?
The food is delicious. （变感叹句）
________  ________ the food is!
Where is the post office?  Could you tell me?（合为一句）
Could you tell me ______ the post office ______?
Is she good at English? Do you know? （合为一句）
Do you know _______ she ______ good at English?
我想知道他为什么这么生气。（完成译句)
I ________ ________ he is so angry.