After the war, American shipping became vulnerable to attacks by pirates.

simple sentence (my answer)
compound sentence
complex sentence
compound complex sentence

Correct again! =)

thanks :)

You're welcome.

Simple sentence:

After the war, American shipping became vulnerable to attacks by pirates.

Compound sentence:
After the war, American shipping became vulnerable to attacks by pirates, and the government had to take measures to protect the ships.

Complex sentence:
Because of the war, American shipping became vulnerable to attacks by pirates, which led to the government taking measures to protect the ships.

Compound-complex sentence:
After the war, American shipping became vulnerable to attacks by pirates, so the government had to take measures to protect the ships, but despite their efforts, some ships still fell victim to pirate raids.

Simple sentence (my answer): After the war, American shipping became vulnerable to attacks by pirates.

Compound sentence: After the war, American shipping became vulnerable to attacks by pirates, so the government implemented new security measures.

Complex sentence: Since the war had ended, American shipping became vulnerable to attacks by pirates.

Compound complex sentence: After the war had ended, American shipping became vulnerable to attacks by pirates, so the government implemented new security measures to protect it.