室性奔马律由于发生在（）时期，听诊时在（）之后，故通常称为（）。
参考答案：舒张期较早、S2、舒张早期奔马律
—It's not just the government's duty to protect the _____.
—I agree. My grandpa often _____ up garbage for recycling and takes good care of animals and plants.
He is a good example to us. [ ]
A. environment; picked
B. environments; pick
C. environment; picks
D. environment; picking
雷诺准数Re≥4000时，一定是层流流动。
