Wine, flowers, ______ foods, and small items for the house all make good hostess gifts.
A. feature
B. quality
C. specialty
D. characteristic
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Ustilago maydis侵染引起()。
A. 玉米瘤黑粉病
B. 玉米丝黑穗病
C. 玉米大斑病
D. 玉米小斑病
Na2S 溶液的质子条件式为
A. c(H+ )+ c(HS- ) + 2 c(H2S) = c(OH- )
B. c(H+ )+c(Na+ ) = c(HS - )+2 c(S2- ) + c(OH- )
C. c(H+ )+ c(H2S) = c(HS - ) +2 c(S2- )+ c(OH- )
D. c(H+ )+ c(HS- ) + c(H2 S) = c(OH- )
Please RSVP ____ Thursday, February 16. We hope to see you there!
A. before
B. on
C. by
D. after
如何消除伺服电动机的“自转”现象()
A. 增大伺服电动机的电压
B. 增大伺服电动机的相位
C. 增大伺服电动机的转子电阻
D. 以上都不对