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Neap tides occur only ().

A.at a new or full Moon

B.when the Sun，Moon，and Earth are in line

C.at approximately 28-day intervals

D.when the Moon is at quadrature

【B12】

A．at first

B．at all

C．at large

D．at times

【C6】

A．at times

B．at one time

C．at odd times

D．at all times

A．at first

B．at all

C．at large

D．at times

The highest pressure in a diesel engine cylinder normally occurs _____.

A.at TDC

B.before TDC

C.after TDC

D.during air starting

A．At first

B．At last

C．At times

Neap tides occur ______.

A.at the start of spring, when the Sun is nearly over the equator

B.only when the Sun and Moon are on the same sides of the Earth and are nearly in line

C.when the Sun and Moon are at approximately 90°to each other, as seen from the Earth

D.when the Sun , Moon, and Earth are nearly in line, regardless of alignment order

A．at first

B．at all

C．at large

D．at times

According to the author, it is best for asthmatics to take their medicines ______.

A．at steady rates

B．each morning and evening

C．when the disease occurs

D．at mid-afternoon

【C9】

A．at a time

B．at times

C．at time

D．in time