In our class, when the bell rang and the teacher closed his book, it was a ______ for everyone to stand up.

A. signal        B. chance          C. mark            D. measure

In our class, when the bell rang and the teacher closed his book, it was a ______ for everyone to stand up.

A. signal        B. chance          C. mark            D. measure

In our class, when the bell rang and the teacher closed his book, it was a ______ for everyone to stand up.

A. signal        B. chance          C. mark            D. measure

In our class, when the bell rang and the teacher closed his book, it was a ______ for everyone to stand up.

A. signal        B. chance          C. mark            D. measure

In our class, when the bell rang and the teacher closed his book, it was a ______ for everyone to stand up.

A. signal        B. chance          C. mark            D. measure

In our class, when the bell rang and the teacher closed his book, it was a ______ for everyone to stand up.

A. signal        B. chance          C. mark            D. measure

In our class, when the bell rang and the teacher closed his book, it was a      for everyone to stand up.

In our class, when the bell rang and the teacher closed his book, it was a      for everyone to stand up.

A．signal            B．chance           C．mark             D．measure

In our class ,when the bell rang and the teacher closed his book ,it was a ________for everyone to stand up .

. In our class, when the bell rang and the teacher closed his book, it was a ______for everyone to stand up.

   A. mark                        B. chance              C. signal               D. measure