Jenny went into the room, took off  her coat and ______ down on a sofa.

A．sits

B．sat

C．is sitting

D．will sit

MDP拥有一个下列哪种有机键（）。

A.P-C-P键

B.P-O-P键

C.P-S-P键

D.P-N-P键

E.P-H-P键