用动词的正确时态填空Our desks and chairs ________________ (make) of wo

用动词的正确时态填空
Our desks and chairs ________________ (make) of wood.The paper of books and newspapers ______ also ___________ (make) from wood.Even some kinds of cloth __________________ (make) from it.Many people ____________ (burn) wood to keep themselves warm in winter.Indeed,wood _______ (be) important in our everyday life.
Where ________ wood __________ (come) from?It ________________ (take) from trees which _____________(grow) in the mountains._________ you ____________ (know) how it ____________ (get) to us from the mountains?
First of all,trees ___________(cut) down when they ______________(grow) big enough.Then their branches _______________ (cut) off,and logs _______________(make).These heavy logs ________________(put) together in different ways and _________________ (take) down to the foot of the mountains.Some of them _________________ (float使漂流) down the small rivers and others _________________ (carry) down on trains.
Big trees ________________(cut) down in the mountains every year.Then young ones ______________________ (must,plant) so that we ______ always ________________ (can,have) enough wood.We have to take good care of mountains so that they __________ always _________________ (may,cover) with growing trees.

1.are made.
2.are made
3.are made
4.burn
5.is
6.doed
7.is taken
8.grow
9.Do
10.know
11.is got
12.are cut
13.grow
14.are cut
15.are made
16.are put
17.are taken
18.are floated
19.are carried
20.are cut
21.must be planted
22.can
23.have
24.may
25.be covered