若关于x的一元二次方程x2+kx+4k2-3=0的两个实数根x1，x2，且满足x

John, who is seventeen this year, usually eats ____ his father does. No wonder he is growing taller. [ ]

A. twice more than as much as

B. more than twice as much as

C. twice as much as more than

D. twice as more than much as

艺术人像画面的线型是各种相连的线条构成的人物与景物的（）的形态。

A、内在

B、外观

C、虚拟

D、联想

人参的煎服方法（）

A.烊化

B.后下

C.先煎

D.包煎

E.另煎

胰腺癌易发生早期转移的原因有（）

A.胰腺周围脏器较多

B.胰腺血管、淋巴管丰富

C.胰腺腺泡无包膜

D.胰腺距离腹主动脉较近

E.胰腺癌发展较快

包装中可能含有哪些有害物质？