Give the correct form of the verbs or the words in brackets

Give the correct form of the verbs or the words in brackets
1.You should learn how ( keep)...the environment clean
2.If he (be )....taller,he would be able to join the police
3.Yesterday,mrs Hoa was making cakes when i ( phone) ....her
4_Recently,life in our province ( change)....dramatically
5.Thank you for (look)...after my grandparents while i was away last week
6.He is a famous ( science )....in the world