2．$\int_{-\frac{1}{2}}^{\frac{1}{2}}{(2+x)\sqrt{1-4{{x}^{2}}}\text{d}x}=$()．
A. $\frac{\text{ }\!\!\pi\!\!\text{ }}{2}$
B. $\frac{\text{ }\!\!\pi\!\!\text{ }}{4}$
C. $0$
D. $-\frac{\text{ }\!\!\pi\!\!\text{ }}{4}$
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7．$\int_{0}^{2}{\,\sin \left| x-1 \right|\text{d}x}=$()．
A. $0$
B. $1-\cos 1$
C. $2(1-\cos 1)$
D. $4(1-\cos 1)$
8．设$a>0$，则$\int_{0}^{a}{\frac{\text{d}x}{x+\sqrt{{{a}^{2}}-{{x}^{2}}}}}=$()．
A. $\frac{\text{ }\!\!\pi\!\!\text{ }}{2}$
B. $\frac{\text{ }\!\!\pi\!\!\text{ }}{4}$
C. $\frac{\text{ }\!\!\pi\!\!\text{ }}{6}$
D. $\frac{\text{ }\!\!\pi\!\!\text{ }}{8}$
9．$\int_{0}^{1}{\frac{2x}{(x+1){{({{x}^{2}}+1)}^{2}}}\text{d}x}=$()．
A. $\frac{1\text{+}\ln 2}{2}$
B. $\frac{1\text{+}\ln 2}{4}$
C. $\frac{1}{2}+\frac{\ln 2}{4}$
D. $\frac{1}{2}-\frac{\ln 2}{4}$
10．从原点向曲线$y=1-\ln x$作切线，则由切线、曲线和$x$轴围成图形的面积为()．
A. $\frac{1}{2}{{\text{e}}^{2}}+\text{e}$
B. $\frac{1}{2}{{\text{e}}^{2}}-\text{e}$
C. ${{\text{e}}^{2}}+\text{e}$
D. ${{\text{e}}^{2}}-\text{e}$
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