In the modern technological world the sea offers many （) to help mankind survive.

She is very careful. She ______ very few mistakes i

She is very careful She ______ very few mistakes in her work A．doesB．makesC．takesD．gets请帮忙给出正确答案和分析，谢谢！

Since Lucy practiced the violin yesterday her mom_____her______ today.A.let...inB.let...

Since Lucy practiced the violin yesterday, her mom_____her______ today A let inB let offC let outD let down请帮忙给出正确答案和分析，谢谢！

已知sinα=－3／5 且α∈（3π／2 2π) 则tan2α的值等于（）

已知sinα=-3 5，且α∈(3π 2，2π)，则tan2α的值等于（）。A -7 24B 21 8C -3 2D 24 7请帮忙给出正确答案和分析，谢谢！

椭圆x2＋my2=1的焦点在y轴上 长轴长是短轴长的2倍 则m的值是__________.

椭圆x2+my2=1的焦点在y轴上，长轴长是短轴长的2倍，则m的值是__________ 请帮忙给出正确答案和分析，谢谢！

在等差数列{an}中 已知a1＋a2＋a3＋a4＋a5=15 则a3= （）。A.3B.4C.5D.6

在等差数列{an}中，已知a1+a2+a3+a4+a5=15，则a3= （）。A 3B 4C 5D 6请帮忙给出正确答案和分析，谢谢！

Scientists will have to___new approaches of increasing

Scientists will have to___new approaches of increasing the world’s power supply A put up withB catch up withC stand up forD come up with请帮忙给出正确答案和分析，谢谢！

男孩性早熟认定的年龄是A.八岁前开始性发育B.十岁前开始性发育C.

男孩性早熟认定的年龄是A 八岁前开始性发育B 十岁前开始性发育C 没有正确答案D 十一岁前开始性发育

Sian’s display of ill temper completely____ my daugh

Sian’s display of ill temper completely____ my daughter’s birthday party A damagedB destroyedC spoiltD hurt请帮忙给出正确答案和分析，谢谢！

仲裁裁决书自作出之日起即发生法律效力。

仲裁裁决书自作出之日起即发生法律效力。此题为判断题(对，错)。请帮忙给出正确答案和分析，谢谢！

Your bill including room service and the meals you had here _____ one hundred and seventy

Your bill, including room service and the meals you had here,_____ one hundred and seventy-five dollars A adds up toB makes upC counts upD gets together请帮忙给出正确答案和分析，谢谢！