胆固醇生物合成的限速酶是
A. HMG-CoA合酶
B. HMG-CoA裂解酶
C. HMG-CoA还原酶
D. MVA激酶
E. 乙酰CoA羧化酶
She felt dizzy and had to ______ something to steady herself.
A. hold onto
B. hold up
C. hold forth
D. hold down
Jonnie was not barely able to walk without help because of the bad injury in his left leg.()
A. was not
B. without help
C. because of
D. bad
That tragedy distressed me so much that I used to keep indoors and go out only （） necessity．
A. within reach of
B. for fear of
C. by means of
D. in case of
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