Today, while I was doing my grammar exercises I found an unusual answer in the answer key . I am working on passive structure. In one of the exercises the books says that the correct answer is:

the boat hit a rock and sank quickly.

but i think the correct answer is:

the boat hit a rock and was sunk quickly.

because I think it can't sink by itself! I mean, if I say " I sank something" it means I did it in the past! In this case this sentences mean the boat sank another thing!

What do you think ?

The book I referred to: Grammar in Use (Raymond Murphy-third edition)

  • 2
    We can't tell you if the answer is correct without seeing the question....
    – Hellion
    Commented May 27, 2015 at 18:04
  • 2
    Many verbs (like sink) can be used either intransitively (The ship sank) or transitively, with a causative sense (The iceberg sank the ship). If a transitive sentence with sink gets passivized (The ship was sunk), it has the same meaning as the intransitive sentence, but implies that the sinking was caused by something outside the ship. Commented May 27, 2015 at 18:19

3 Answers 3


because I think it can't sink by itself

When you think that, it's always a good idea to check a dictionary.

Merriam-Webster tells us this about sink:

intransitive verb
a : to go to the bottom : submerge
transitive verb
a : to cause to sink

As you can see, the verb can be intransitive, meaning that ships can sink by themselves. There is nothing wrong with "the ship sank".

At the same time, it can be used transitively, in the way you considered. Someone can sink a ship, and a ship can be sunk (by someone).

  • 1
    Well, you can speak as though ships can sink by themselves, but that doesn't mean they actually can. Grammar is not physics.
    – Greg Lee
    Commented May 27, 2015 at 19:10
  • @GregLee Why can't ships sink by themselves?
    – phoog
    Commented May 28, 2015 at 0:48
  • @phoog, I don't have a position on whether ships can sink by themselves.
    – Greg Lee
    Commented May 28, 2015 at 1:13

I think they are both possible.

Things do sink, though. They sink themselves. The sun sinks itself down below the horizon. People sink drinks down themselves.

And, of course, they get sunk - by the things doing the sinking, and the things causing the sinking, like the rocks, or the accident, causing the sinking of the ship.

  • 1
    Mentioning a contrived reflexive form is a bit confusing. If a ship sinks, it does not sink itself. It just sinks.
    – oerkelens
    Commented May 27, 2015 at 18:34

Both sentences are correct, but they both use a different form of the verb to sink.

The two forms are:

  1. Transitive (= with object)

    Something/someone sinks something/someone else.

  2. Intransitive (= without object)

    Something/someone sinks.

I hope that helped!

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