放射性物质对生物尤其对人体的效应，主要取决于接受辐射照射量的轻重程度。
参考答案：对
The invention of steam engine greatly sped up the industrial revolution, which _____ a lot to the take-off of the world.
A．led
B．contributed
C．constructed
D．exposed
不得驾驶具有安全隐患的机动车上道路行驶。
