工程项目实施阶段，节约工程资源的主要途径是( )。A．缩短工期B．做好前期资源准备

阅读理解。

    When the world was very young, people lived only in hot places. They did not live in

cold places because they could not keep warm there.

    At first men do not know how to make a fire. Sometimes trees were hit by lightning.

Then a fire was started. People took some of the fire near their homes. A fire was very

important for three reasons. It kept them warm. Wild animals were frightened when they

saw it. And when food was cooked, it tasted much better.

    But men did not know how to make a fire. When they had a fire, they did not let it

stop burning. If it went out (熄灭), they could not start it again. They had to wait for

lightning to start another fire. Sometimes they had to wait for years.

    Later, they learned how to make a fire. But it was not easy to make something burn. 

    Now we have matches. We can carry them in our pockets and make a fire when we want

to.

1. "When the world was very young" means "_____". [ ]

A. before liberation (解放)

B. in the following years

C. before long

D. millions of years ago

2. People found that _____. [ ]

A. the cooked food tasted better than the uncooked food

B. the uncooked food tasted much better than the cooked food

C. wild animals enjoyed the cooked food

D. wild animals kept warm near the trees

3. People didn't let a fire stop burning because _____. [ ]

A. they were not able to make a fire

B. they liked to wait for lightning

C. it rained now and then

D. they didn't like to make a fire

4. Now we can make a fire _____. [ ]

A. by lightning

B. if it is necessary

C. for three reasons

D. in our pockets

Many countries are now setting up national parks _     animals and plants can be protected.

A．which

B．whose

C．when

D．where

牙周翻瓣术后能探诊的时间是（）

A.术后1周

B.术后10天

C.术后2周

D.术后3周

E.术后7周

在中子测量中，按其能量可分为（）。

A.慢中子，能量<1keV

B.中速中子，能量为1～10keV

C.中速中子，能量为1～100keV

D.快中子，能量为0.1～20meV

E.快中子，能量为1～20meV

视交叉中部病变时，视野改变为

A．双眼鼻侧偏盲
B．双眼鼻侧向限盲
C．右眼鼻侧盲
D．左眼鼻侧盲
E．双眼颞侧偏盲