未知题型 应选：A.it B.that C.one

未知题型 有一平板上的层流边界层，当来流流速U0=0.16m/s，如Rex=3×105，求0.48和0.88处的流速ux和uy。

单项选择题 Cartons are quite fit for ocean transportation, and they are ______ used in our shipments to other ports to the entire satisfaction of our clients. A．intensively B．extensively C．intensive D．intensive