– Mum, I've been studying English since 8 o'clock. _____ I go out and play with Tom for a while?– No, I'm afraid not. Besides, it's raining outside now.
A:Can't
B:May not
C:Won't
甲、乙两艘轮船同时从一个码头向相反方向开出,航行了5小时,两船相距225千米,甲船每小时行19.5千米,乙船每小时行多少千米?
填空完成问题:
痰是气管分泌的黏液和黏液粘住的灰尘、细菌等。