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

<ins id="pccqi"><output id="pccqi"></output></ins>

單項選擇題

A fire starts when the following （） factors come together.

A.combustible material
B.ignition source
C.oxygen
D.A and B and C

你可能感興趣的試題

單項選擇題

（） can be operated independently or locked together and operated as a twin-job cranes of double capacity.

A.Two derricks
B.A derrick and a crane
C.Two cranes
D.A crane and a winch

單項選擇題

Some cranes are mounted in pairs on a common platform which can be rotated through（）.

A.360°
B.270°
C.180°
D.90°

<dd id="lo7gj"><acronym id="lo7gj"></acronym></dd>

<pre id="lo7gj"></pre>