铅酸蓄电池的结构通常是由构成( )。
A. 正负极板
B. 隔板
C. 容器
D. 电解液
E. 双氧水
1.This is _________ boy. That girl is _________.
A. an 8-years-old; 6 years old
B. an 8-year-old; 6 years old
C. an 8-year-old; 6-year-old
D. a 8-year-old; 6-year-old
2.Mr. Smith has two __________, both of them are teachers in a college.
A. brothers-in-laws
B. brother-in-laws
C. brothers-in-law
D. brother-in-law
3.After the final exam, I will have a ________ vacation in Hainan.
A. 5 day
B. 5-day
C. 5 days
D. 5-days
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