Trees ______every spring in North China.

A．have planted

B．will plant

C．were planted

D．are planted

* * 血性分泌物最常见于（）

A.乳腺癌

B.急性乳腺炎

C.乳腺纤维瘤

D.乳腺小叶增生

E.乳腺导管内良性乳突状瘤