易通过血脑屏障的磺胺药是（）。

A．磺胺甲基异恶唑

B．磺胺异恶唑

C．磺胺嘧啶

D．磺胺邻二甲氧嘧啶

E．磺胺噻唑

All echo-sounders can measure the（）.

A.actual depth of water

B.actual depth of water below keel

C.average depth from waterline to hard bottom

D.average depth of water to soft bottom