The age limit of underwater rugby is __________.

What is the unique system of underwater irrigation and drainage in Xinjiang Province?

有缆遥控潜水器是下列哪个( ) A: UUV(Unmanned Underwater Vehicle) B: AUV(Autonomous Underwater Vehicle) C: HOV(Human Occupied Vehicles) D: ROV(Remote Operated Vehicle)

Theword“immersed”inthesecondparagraphmeans“____”.（） A: carry B: take C: arouse D: underwater

An underwater railroad tunnel beneath the English Channel now connects the UK with other parts of Europe.

How about the traffic in the underwater traffic tunnel A: Heavy. B: Light. C: Fast. D: Dangerous.

The first lesson I learned as a soldier was never to __ ____ the enemy. A: underestimate B: underpaid C: underdeveloped D: underwater

Ships are often sunk in order to create underwater reefs （暗礁） perfect for scuba diving （水肺式潜泳） and preserving marine __1__.

The research team decided to use an underwater saw to cut the ______ship into sections before lifting it up. A: electrical B: electric C: electricity D: electrifying

The research team decided to use an underwater saw to cut the ______ship into sections before lifting it up. A: electrical B: B. electric C: electricity D: D. electrifying