【单选题】

# 设$f(x)=x^2$,$g(x)=2^x$, 那么 $f \circ f \circ g=$

A.
$2^{x^4}$
B.
$2^{4x}$
C.
$x^{2^{2x}}$
D.
$x^{2^{x^2}}$

A

A.

B.

C.

D.

## 【单选题】$y=\log_x 2$的反函数为

A.
$y=2^{1/x},x >0$
B.
$y=2^{x},x >0$
C.
$y=2^{1/x}, x \neq 0$
D.
$y=2^{1/x},x >0, x \neq 1$

A.

B.

C.

D.

## 【单选题】函数$f(x)=\frac{e^x-e^{-x}}{2}$的反函数是

A.
$y=\ln(x+\sqrt{x^2+1}), x\in \mathbb{R}$
B.
$y=\ln(x+\sqrt{x^2+1}), x>0$
C.
$y=\ln(x-\sqrt{x^2+1}), x\in \mathbb{R}$
D.
$y=\ln(x-\sqrt{x^2+1}), x>0$

## 【单选题】方程$\cos(2x)=0.5$的解集为

A.
$k \pi + \frac{\pi}{3},k\in \mathbb{Z}$
B.
$k \pi + \frac{\pi}{6},k\in \mathbb{Z}$
C.
$3k \pi + \frac{\pi}{3},k\in \mathbb{Z}$
D.
$2k \pi + \frac{\pi}{3},k\in \mathbb{Z}$

## 【单选题】In _____, nodding your head up and down means “yes”, while in some parts in ______, this motion can mean “no.” But in ______, nodding your head is a polite way to say “I heard you.”

A.
the United States; southeast Asia and China; Greece and Turkey;
B.
Greece and Turkey; southeast Asia and China; the United States;
C.
the United States; Greece and Turkey; southeast Asia and China
D.
Greece and Turkey; the United States; southeast Asia and China