有关岩石圈的叙述，正确的是 （ ）
| A．岩石圈属于地壳的一部分，是由岩石构成的 |
| B．岩石圈是由地壳和上地幔顶部（软流层以上）部分组成 |
| C．岩石圈与生物圈没有联系 |
| D．岩石圈的上部是软流层 |
People go out with masks,________.
| A．fear of swine flu. | B．afraid of swine flu. |
| C．fearing of the pig flu. | D．being afraid of swine flu.. |
The dead rate is _____ pigs and recovery usually ______ within 7-10 days.
A low in; occursB.rich in;happens
C.high in; came aboutD.poor in;took place
_____ three influenza type A virus subtypes(子类型) have been found in pigs.
| A．By far | B．As far as | C．So far | D．Till far |
_____, experts point out that students can easily fail at starting their business because of a lack of preparations.
| A．But | B．However | C．while | D．though |
It has always been the _____ of our goverment to encourage graduates to start their business.
| A．plan | B．campaign | C．procedure | D．policy |