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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相关考题
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单项选择题
By the concrete being too "green", the author means that the concrete has
A．become cracked.
B．not yet cured.
C．not dried out.
D．not settled in place. -
单项选择题
The private postal services of the nineteenth century claimed that they could do which of the following better than the government
A．Deliver a higher volume of mail.
B．Deliver mail more cheaply.
C．Deliver mail faster.
D．Deliver mail to rural areas. -
单项选择题
In 1863 the United States government began providing which of the following to mail carriers
A．Housing.
B．A salary.
C．Transportation.
D．Free postage stamps.
