99色精品-9色在线-99色在线-99色视频国产欧美日产一区二区三区_亚洲精品亚洲人成在线观看_四虎在线精品永久观看_免费一级a一片久久精

<pre id="u5eg5"><strong id="u5eg5"></strong></pre>

單項(xiàng)選擇題

A large metallic device，mounted directly in the piping (usually located at the dock near the point where the vapor hose is attached)，designed to prevent the passage of a rapidly moving flame through the piping is called a（）.

A.flame arrestor
B.flame screen
C.detonation arrestor
D.detonation blocker

你可能感興趣的試題

單項(xiàng)選擇題

A large basin cut into the shore，closed off by a caisson，and used for dry docking of ships is known as a（）.

A.slipway
B.graving dock
C.ground warp
D.caisson dock

單項(xiàng)選擇題

A jack-up drilling unit elevated on the Outer Continental Shelf must have a fog horn that will sound（）.

A.a 2-second blast every 20 seconds
B.a 4-second blast every 20 seconds
C.an 8-second blast every 30 seconds
D.a 10-second blast every 30 seconds