1.-May I borrow your pen?I can't find mine.

1.-May I borrow your pen?I can't find mine.
-Sorry,mine is broken,maybe Tom can lend ____ to you.
A.it
B.these
C.them
D.one
我选A,在这里it和one有什么区别么?
2._____ was Jim that caught the thief on the street yesterday.
A.This B.They C.It D.That
这几个词分不清,什么时候用哪个呢?