A、<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/15177952347022f890c35600c4b51ab8af80a9b624519image54.png">
B、<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/1517795234766adfb8309f1294bbea090baa43ccb5217image55.png">
C、2
D、4