Homing pigeon is useful as a ______ carrier because when taken from home, it will return atthe first opportunity.
C
暂无解析
Mrs.Smithlockedboththefrontandthebackdoorsbeforeshewenttobed______thatsomeonemightstealintothehouseatnight.
Shewasso______thenoisethatshesentthechildrentobed.
In1900,theenergyderivedfromburningpetroleumwasonlyfourpercent______ofcoal.
Thosewhochangemobilephonestoofrequentlywillhavetopayforbeing______.