碳素钢的五大元素中,锰和()是有益元素,是一种脱氧剂。
参考答案:硅
阅读理解。
Hello, I'm Sonia. I'm an English girl.Iam in China(中国)with my grandparents.I like spoors very
much.I have a great sports collection.I have four baseballs, three soccer balls, nine tennis rackets
and seven volleyballs.I often play tennis with my grandfather.
1.Sonia is a ______ girl.
A.English
B.China
C.Americ,an(美国的)
D.Chinese
2. Sonia is in______with her grandparents.
A. America
B. England
C. China
D.London
3. Does Sonia like sports?
A. Yes, she is
B.No, she doesn't
C.Yes, she does
D.I don't know
4. Sonia has _______ volleyballs.
A. eight
B.five
C.ten
D.seven
5. Sonia often plays _______ with her grandfather.
A. soccer
B. volleyball
C. tennis
D.ping-pong
A.mgtgθ
B.mgsinθ
C.μmg
D.μmg