问三道英语选择题,要理由
1.She was _____her early twenties when she went abroad.
A.at B.on C.of D.in
2.We shall go there _____we are free.
A.however B.wherever C.whatever D.whenever
3.I was just about to go shopping_____a friend of mine came to see me.
A.since B.while C.because D.when