there must be something seriously wrong with the machine

there must be something seriously wrong with the machine
请翻译全句,其中seriously是副词,在中文意思中不是用来修饰wrong的吗,为什么在原句中却是修饰something的,另有为什么不能用serious呢
2）2)have you seen a pen?
is it _______black one i think i saw it somewhere
A)the
B)a
请问空格处后是特指那只黑色的笔,为什么不能用the呢
3）this factory is quite different from______before
A)what it was
B)that is was
C)which it was
D)what was it
请说明选择的理由,为什么不能选别的答案
4）we were all surprised when he made it clear that he_____office soon
A)leaves
B)would leave
C)left
D)had left
请说明选择的理由,为什么不能选D,并且翻译全句