A red light is often used as a danger _____.A. signalB. signC. warningD. reminder

Copper is often used as an electrical conductor because it _____.

Which of the following italicized parts is used as an object complement？A．He is often hear

Which of the following reflexive pronouns（反身代词)is used as an object？A．John often put h

Which color does Americans often use to express heat？A．Pink.B．Red.C．Blue.D．Black.

Rhetorically, homonyms are often used as puns.（)

The oil must have been used up,______the light went out.A．becauseB．forC．sinceD．as