关于孕激素的叙述下列哪项是错误的：（）
A.由卵巢和肾上腺髓质产生
B.胎盘也可产生
C.在肝脏中代谢
D.降解为孕二醇
E.卵泡期含量极低
参考答案：A
P型喷油泵适用于循环供油量（）的柴油机上。
A.较小
B.小
C.较大
D.大
He is cleaning his room.
She is writing an e-mail.
He is cooking.
She is sleeping.
She is walking in a park.