单项选择题

In mixing concrete, one of the desires the amateur must resist is to________.

A．break off a corner to see if the "green" has gone
B．leave the form on too long
C．strip off the forms a day after the concrete has properly hardened
D．use too much water

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热门试题

单项选择题

The best title for this selection would be:________.

A．Concrete and Its Uses
B．Rules for Working with Concrete
C．Concrete, the Homeowner's Joy
D．Concrete, a Test of Character

单项选择题

What does the passage mainly discuss

A．The increase of private mail service.
B．A comparison of urban and rural postal services.
C．The development of government postal system.
D．The history of postage stamps.