甲、乙两物体的质量之比为m甲:m乙=1:4,若它们在运动过程中的动能相等,则它们动量大小之比p甲:p乙是 ( )
A.1:1
B.1:2
C.1:4
D.2:1
答案:B
句型转换。
1. My parents should allow me to study with friends.(改为同义句)
I should ______ ______ to study with friends.
2. They oft en clean their classroom after school. (改为被动语态)
Their classroom ______ often ______ by them after school.
3. Li Lei gave Tom a new pen last week. (改为被动语态)
A new pen ______ ______ ______Tom last week.
4. It took him ten years to finish writing the book. (改为同义句)
He ______ ten years ______ the book.
5. They will publish these story-books next month. (改为被动语态)
These story-books ______ ______ ______ next month.
某地2001年平均人口数为100 000,该地防疫站收到2001年发病的菌痢传染病报告卡323张,剔除重复,实际报告的菌痢患者为260人,在此260人中有 3人发病2次,则该地菌痢的报告发病率为
A.323/10万B.260/10万C.326/10万D.263/10万E.257/10万