第二产程心脏负担最重是由于（）。

A.腹压加大，内脏血液涌向心脏

B.周围阻力更为增高

C.心排血量及平均动脉压增高

D.肺循环压力增高

E.以上说法都正确

—This kind of rice tastes nice.

—Yes, it _____ in northeast of China.[ ]

A. was grown

B. has grown

C. is grown

D. is growing