7. We should prepare food carefully before turning on the stove.

                   Food  ___should be prepared carefully before turning on the stove_________

8. They did the work excellently.

                  The work ____was done excellently_________

9. You mustn’t use this machine after 5.30 pm.

                  This _____machine mustn't be used after 5.30pm___________

10. People say that he is a good teacher.

                  He is said ____to be a good teacher______________________________

11. They did the work excellently.

                  The work _____was done excellently_______

12. They began using that computer three months ago.

                  That computer has___been used for three months_____________________

13. People celebrate Passover in Israel in late March or early April.

                  Passover ______ in Israel is celebrated in late March or early April_______

14. The Prime Minister will open three more new schools in the town next autumn.

                  Three more new schools ____will be opened in town by the Prime Minister next autumn______________

15. Both men and women wear Jeans.

                   Jeans ____are worn by both men and women________     

16. We must stop their actions.         

                    Their actions _____must be stoped____

B

1 goes

2 drinking

7C 8A

\(\sqrt{x^2+2x+1}-\sqrt{x+1}=0\left(đk:x\ge-1\right)\)

\(\Leftrightarrow\sqrt{\left(x+1\right)^2}-\sqrt{x+1}=0\)

\(\Leftrightarrow\left|x+1\right|-\sqrt{x+1}=0\)

\(\Leftrightarrow x+1-\sqrt{x+1}=0\)

\(\Leftrightarrow\sqrt{x+1}\left(\sqrt{x+1}-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+1=0\\x+1=1\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=-1\left(tm\right)\\x=0\left(tm\right)\end{matrix}\right.\)

13A 14D