_________(53)A..they B./C.that D.who

Some component parts should be replaced regularly because______.A．they are outdatedB．they

Before children start speaking________.A、they need equal amount of listeningB、 they nee

Street vendors are not always reliable because______.A．they sell illegal goodsB．they are n

________（47）A.they can give people unprecedented

________（48）A.they can give people unprecedented

________（49）A.they can give people unprecedented