Sincewehaveafocusedsubject，weshouldnottalk________.
A、atonceD
譯文：既然我們已經有了命題， 我們就不應漫無邊際地交談。 此題考查對固定短語的掌握情況。 at once 立刻; at hand在附近，在手頭，即將發生; at intervals 間或，不時; at random 隨便，任意。
Thefarmingmethodshavebeen________improvedwiththeinventionofthenewmachine.
Sincewehaveafocusedsubject，weshouldnottalk________.
YouarethemostdirectyoungwomanIhaveever_______.
Thevehiclewastravelingatspeeds________90milesperhour.
Theoutlineofrooftopsandchimneys________againstthepalesky.
