小儿体重增长的正常波动范围是（）
A.50%左右
B.40%左右
C.30%左右
D.20%左右
E.10%左右
参考答案：E
要用圆形铁片截出边长为2的正方形铁片，选用的圆形铁片的半径至少是______．
They were asked to avoid（）any water which had not been boiled.
A.drinking
B.not to be drunk
C.to drink
D.having
