_________(60)A.normal B.necessaryC.domestic D.for

A semiconductor is a material with a _____.A.conductivity higher than a normal conductorB.

American colleges and universities accept______.A．normal students onlyB．blind students onl

_________(62)A.off B.onC.up D.for

_________(54)A.at B.inC.on D.for

_________(58)A.by B.onC.in D.for

_________(58)A.normal B.good C.main D.side