单项选择题
The canvas covering of fire hose is called the（）.
A.casing B.outer hose C.line cover D.jacket
单项选择题 The brickwork surrounding the firebox of a boiler is known as（）.
单项选择题 The blocking or absence of fire dampers can cause（）.
单项选择题 The bilge pump on a fishing vessel（）.
