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)