DOHC表示()。
参考答案:顶置式双凸轮轴
You can never know ________ when she received our nice birthday presents.
A.how Mary was excited
B.how excited Mary was.
C.How excited was Mary
D.Mary was how excited
下列各组金属最合适用氢气或CO把它们从化合物中还原出来的是( )
A.Ca、Mg
B.Al、Fe
C.Fe、Cu
D.Hg、Ag