Don’t use water to put out the fire if oil catches fire. As is known oil float on water.

问题补充：

Don’t use water to put out the fire if oil catches fire. As is known, oil float on water.

A. shall

B. must

C. may

D. will

答案：

A. shall

B. must

C. may

(答案→)D. will

解析：考查情态动词用法。本题中的will表示倾向性，如The door will not open。门无法打开。句意：如果油着火了，请不要用水来灭火，众所周知，油是会漂浮在水的上面的。故D正确。