所谓汽水共腾是指（）。
A.蒸汽带水太多
B.炉水中含汽泡太多
C.炉水表面形成很厚不易消散的泡沫层
D.A十B十C
参考答案：C
24和42的最大公因数是（ ），24乘（ ）就得24和42的最小公倍数。
--- I hear you have an experience in the Roya1 Air Force. Is that true？
--- Yes. I in the Royal Air Force for six years.
A．served
B．had served
C．joined
D．have joined
