简述腐蝇、黑蝇、家蝇第四纵脉特征。
参考答案：
腐蝇第四纵脉微弯曲；黑蝇第四纵脉直行；家蝇第四纵脉强弯曲。
An emergency meeting will be held tomorrow, at which the bill ________ to pass.
A．is expected
B．will be expected
C．expects
D．will expect
