Our teacher looked here and there on our playground ______ looking for something.

A．even though

B．even if

C．as if

D．only if

下列疾病中，通常是单侧性听力下降的是（）

A.耳毒性药物中毒

B.老年性耳聋

C.梅尼埃病

D.遗传性耳聋

E.噪声性耳聋