对于边界摩擦,在高速重载之下,可使润滑油在金属界面建立______。
A.物理反应膜
B.物理吸附膜
C.化学反应膜
D.化学吸附膜
参考答案:C
When she woke up, she realized that the things she had dreamt about could not ____ have happened.
A.possibly
B.likely
C.certainly
D.usually
两栖类受精卵的卵裂方式为()。
A、不完全卵裂
B、完全卵裂
C、盘裂
D、表裂