Give the correct tense or form of the words in brackets

Give the correct tense or form of the words in brackets . (1,0 p )

1.. We often take part in many ……………..activities at school. (culture)

2  The Internet has helped students study more……………… (effective)

3.  There are many………..in Viet Nam every year                   ( celebrate)

4  Solar energy does not cause …………….                              (pollute)

     5 ……………. is one of big proplems in the world                     ( forest)