The third officer is ___ (负责)the fire-fighting equipment. A.responsible B.take charge of C.in charge of D.control

9. A.By a gift card. B.By cheque. C.In cash. D.By credit card.

Susan is not at the meeting. She has been absent ______ our meeting for several times. A: from B: B．of C: C．in D: D．at

Where does Miss Li work Where does Miss Li work A: In a school. B: B．In a hospital. C: C．In a restaurant.

______ the difficult situation in the job market, he decided to take night courses at a college. A: In place of B: B．In terms of C: C．In view of D: In front of

Most students study because it’s unavoidable. , there are students who actually enjoy it. A: A．As a result B: B．In addition C: C．In conclusion D: D．By contrast

Word came that 30 firefighters gave their lives to our country _______ national property security. A: A．in exchange for B: B．in response to C: C．in terms of D: D．in contrast with

Lightning bugs can blink themselves because of a chemical substance Lightning bugs can blink themselves because of a chemical substance A．in the head. B．in the tail. C．in the abdomen, D．in the wing. A: in the head. B: in the tail. C: in the abdomen, D: in the wing.

比较C≡C, C=C, C─C, C=C─C=C的键长次序为: C=C─C=C>C─C> C≡C >C=C|C=C─C=C>C─C>C=C>C≡C|C≡C>C=C>C─C>C=C─C=C|C─C>C=C>C=C─C=C>C≡C|C─C>C=C─C=C>C=C>C≡C

下列哪种主链骨架原子排列最能代表两个肽键?() A: Cα—N—Cα—C—Cα—N—Cα—C B: Cα—N—C—C—N—Cα C: C—N—Cα—Cα—C—N D: Cα—C—N—Cα—C—N E: Cα—Cα—C—N—Cα—Cα—C