单项选择题

Vaccines for viral diseases are often produced from ______.

A．plant cells
B．human hormones
C．crop plants
D．bacteria
<上一题 目录 下一题>
热门 试题

单项选择题
All of the following aspects of backpacking are discussed in the passage except ______.
A．wearing several layers of clothing
B．getting maximum use from your pack material
C．improving the warmth of your sleep
D．forecasting the weather
单项选择题
According to the passage, it would be more advantageous to pack ______.
A．a light sleeping hag, pants and shorts, a heavy jacket, and a shirr
B．a light sleeping bag, two pairs of pants, and a heavy jacket
C．a light sleeping bag, two pairs of pants, and a light sweater and shirt
D．a light sleeping bag, pants and shorts, and a light sweater and shirt
相关试题