1.We often (to use) alcohol diluted with water as a solvent.
2. After French, Swedish and German chemists (discover) gallium, scandium and germanium, Mendeleev was recognized the author of the Periodic Law.
3. It is clear that the chemical reaction (to change) the composition and specific properties of this substance.​

1) they didn't go to the cinema

2) she didn't buy a new computer

3) she didn't study for a history test

4) there were not two thousand people at the concert

5) he didn't call 10 minutes ago

6) the film didn't start at 9: 00

    1) did they go to the cinema?

    2)did she buy a new computer?

    3)did she study for a history test?

    4)were there two thousand people at the concert?

    5) did he call 10 minutes ago?

    6)did the film start at 9: 00?

is necessary to protect  animals!   in  this  country  there is a  krasnaya  book  andindividual regions.  animals  assistants  and residents  of the forest,  if  not, then  who will help  the forest.  can not allow  illegal  hunting of  animals.  and  in general i think  that we should not  kill animals  for fun.

1) is my sister  leaving to her place at the moment?   2) i  read  this book yesterday.3) you will play the piano tomorrow.4) we are returning from the museum now.5)our friends  do not  see mary every day.6) did the new school begin  working last year? 7)he often  speaks to me.8)he was  discussing that problem the whole morning yesterday.9)i will be reading this article at two o'clock tomorrow.