施工企业应采取有效的职业病防护措施，为作业人员提供必备的（）。
A、安全交底
B、劳动保险
C、饮食卫生
D、防护用品
参考答案：D
The well was found __________ when we got there.
A．digging
B．to be dug
C．to dig
D．being dug
After the actor told a funny story about his childhood, all the people burst into ______.
A．laugh
B．laughter
C．laughing
D．laughers
