问题

The researchers found clear and convincing evidence _________ happiness is the key when it comes to better health and longer lives.

A:where
B:whether
C:how
D:that;

正确答案是：

同类题型

The boy has poor eyesight(视力). He_____________ a pair of glasses.

city, it is ______ in July, but itis even _______ in August.

___ have bought the book for me, but thank youall the same

I find _____ not easy to answer this question in English.

Even if you had not been able to see her, you ______ us.