求几道英语选择题答案,要详细解释

求几道英语选择题答案,要详细解释
1.Mary is always——under the weather.
A.traveling B.away from home C.sick D.unconscious
2.At last she left her house and got to the airport, only ________ the plane flying away.
A) having seen
B) to have seen
C) saw
D) to see
3.They assured us that _______ was waiting for they were there to share it
A) what B) whatever C) it D) whoever