It is hard to imagine a student _______doesn't know how to skate in Harbin.
A：whom
B：which
C：what
D：who
天平的左边放一个文具盒，右边放2瓶墨水刚好平衡．如果一瓶墨水质量为x克，那么一个文具盒质量为____克；如果x=100，则文具盒质量为____克．
