1.Don't set yourself up for failure.You chances of achieving your goals are much better____ they're realistic.
A.since B.unless C.if D.ad
这道题为何选C 请指教其中的原理
2.People hold the view that life is 10% what happens to us and 90% ___ we respond to it.
为何这里填how 而不是 what?求指教原理