单项选择题

Researchers discovered that plants infected with a virus give off a gas that ______ disease resistance in neighboring plants.

A．contracts
B．activates
C．maintains
D．prescribes
<上一题 目录 下一题>
热门 试题

单项选择题
The Eskimo is perhaps one of the most trusting and considerate of all Indians but seems to be ______the welfare of his animals.
A．critical about
B．indignant at
C．indifferent to
D．subject to
单项选择题
Dozens of scientific groups ail over the world have been ______ the goal of a practical and economic way to use sunlight to split water molecules.
A．pursuing
B．chasing
C．reaching
D．winning
相关试题