窗洞口一般虽不要求做______，但同样也要方正一致，______。
参考答案：护角；棱角分明，平整光滑
He looks younger ______ his friend; in fact, he is three years senior _______ his friend.
A．to; to
B．than; by
C．than; than
D．than; to
When to go there depends ______ the weather.[ ]
A. in
B. on
C. with
D. of
