凡长度超过几米而又不通风或通风不良的独头巷道，统称为盲巷？
参考答案：
6m
用游标卡尺测得某样品的长度如图1所示，其示数L=______；用螺旋测微器测得该样品的外径如图2所示，其示数D=______．
Passage One
Why was the world market important for the United States agriculture a. It provided evidence that Jefferson’s ideal could be achieved. b. It made farmers less dependent on local bankers. c. It affected the prices that farmers could receive for their crops. d. It decreased the power of the railroads to control farm prices.
