题干
— Tom wants to know if you will have a picnic tomorrow.
— Yes, but if it_______, we'll play chess instead.
A：will rain
B：is raining
C：rains
答案(点此获取答案解析）
C
— Tom wants to know if you will have a picnic tomorrow.
— Yes, but if it_______, we'll play chess instead.
A：will rain
B：is raining
C：rains
轴的非负半轴为角的始边，如果角
、
的终边分别与单位圆交于点
和
，那么
等于