采用混铁炉是为了稳定铁水的()和(),调节高炉和转炉之间的供求平衡。
参考答案:成分;温度
长方形的周长=( )。
—Simon,I wonder _______. —Last Saturday.
A.when the foreign visitors arrived
B.when did the foreign visitors arrive
C.when the foreign visitors will arrive
D.when will the foreign visitors arrive