A. $-x-3z=0$

B. $-x+3y=0$

C. $-x+3z=0$

D. $-y+3z=0$

A. $S=\left\{\frac{\pi}{2}+k \pi \mid k \in \mathbb{Z}\right\}$

B. $S=\{k 2 \pi \mid k \in \mathbb{Z}\}$

C. $S=\{k \pi \mid k \in \mathbb{Z}\}$

D. $S=\left\{\frac{\pi}{2}+k 2 \pi \mid k \in \mathbb{Z}\right\}$

A. $S=\int_{1}^{2}(2x+1)\,dx$

B. $S=\int_{1}^{2}(2x+1)^{2}\,dx$

C. $S=\pi\int_{1}^{2}(2x+1)^{2}\,dx$

D. $S=\pi\int_{1}^{2}(2x+1)\,dx$

A. $\overrightarrow{S A}+\overrightarrow{S B}+\overrightarrow{S C}+\overrightarrow{S D}=4 \overrightarrow{S O}.$

B. $\overrightarrow{S A}+\overrightarrow{S B}+\overrightarrow{S C}+\overrightarrow{S D}=\overrightarrow{0}.$

C. SA+SB+SC+SD=0.

D. S4+SB+SC+SP=SQ.

A. $x=\frac{3}{2}$

B. $x=3$

C. $x=1$

D. $x=\frac{5}{2}$

A. $(B'BC)$

B. $(AB'C')$

C. $(ABC)$

D. $(A'B'C')$

A. A new bridge will be built here.

B. A new bridge is built here.

C. A new bridge was built here.

D. A new bridge has been built here.

A. $\overrightarrow{S A}+\overrightarrow{S B}+\overrightarrow{S C}+\overrightarrow{S D}=4 \overrightarrow{S O}$

B. $\overrightarrow{S A}+\overrightarrow{S B}+\overrightarrow{S C}+\overrightarrow{S D}=\overrightarrow{0}$

C. $\overrightarrow{S A}+\overrightarrow{S B}+\overrightarrow{S C}+\overrightarrow{S D}=2 \overrightarrow{S O}$

D. $\overrightarrow{S A}+\overrightarrow{S B}+\overrightarrow{S C}+\overrightarrow{S D}=\overrightarrow{S O}$