选择题：Imagine how many times restaurants and merchants h

题目内容：

Imagine how many times restaurants and merchants had to change their posted prices during the _____ 1970s, when prices almost doubled.

参考答案：

设区域D是由圆x^2 + y^2 =2ax(a>0)围成，则二重积分∫∫e^-x^2-y^ dv=(

设区域D是由圆x^2 + y^2 =2ax(a>0)围成，则二重积分∫∫e^-x^2-y^ dv=() A 2∫x/2 0, d∫2cose 0, e^r dr

1935年12月9日,北平学生举行声势浩大抗日示威游行时喊的口号是( )(本题3.0分) A、反对华北自治运动 B、打倒日本帝国主义 C、内惩国贼,外

已知a=(4,2),b=(6,y),且a与b平行,则y= A.3B.12C.4/3D.4/3

He ___ to get in touch with them but without success. A) attempted B) attracted