He is worried a lot now, for he has lost a _____of keys today.

Most respondents of the Wall Street Journal poll______.A．are pessimistic about America's general trackB．are optimistic about the country's outlookC．appreciate America's economic recoveryD．feel that they couldn't afford a house 点击查看答案

在填土压实中，羊足碾可用于下列哪种土的压实?()

A、砂土
B、粘性土
C、碎石土
D、以上三类土均可

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