Closed-ring contours indicate that the ground within the ring is ( ). A: lower B: higher C: equal D: either A orB

Ignoring the__________ ring, she put the chicken in the oven and closed the door.

Helen gave her daughter （） A: a ring B: to a ring C: for a ring D: with a ring

The Ring of the Nibelung is generally known as the Ring or the Ring Cycle.

- Who closed the door? -Nobody. It( ) A: was closed by itself B: had closed itself C: was closed itself D: closed itself

A ring homomophism f from a ring R onto another ring S is an isomophism if and only if kerf=0.( )

It was common practice then that when the store owners wantedto go on vacation theysimply . A: closed in B: closed on C: closed down D: closed up

You must keep your eyes （）. A: closed B: close C: be closed D: to closed

The noise of desks___could be heard out in the street. A: opened and closed B: to be opened and closed C: being opened and closed D: having been open and closed

The noise of the desks _____ could be heard in the next classroom. A: being opened and closed B: opened and closed C: having been opened and closed D: to be opened and closed