机场停机坪扩建后，可同时停放8架中小型飞机，具体为（）。
A.3D4C1B
B.2D4C2B
C.3D3B2C
D.2D5C1B
参考答案：D
—John got injured in the game.
—Would it be at least a fortnight ______ he could recover and return to school?
A．when
B．that
C．since
D．before
简述根系分泌物和根际微生物对土壤养分有效性的影响
