conjunction

Each of the highlighted words in the following sentences is a subordinating conjunction:

After she had learned to drive, Alice felt more independent.

The subordinating conjunction "after" introduces the dependent clause "After she had learned to drive."

If the paperwork arrives on time, your cheque will be mailed on Tuesday.

Similarly, the subordinating conjunction "if" introduces the dependent clause "If the paperwork arrives on time."

Gerald had to begin his thesis over again when his computer crashed.

The subordinating conjunction "when" introduces the dependent clause "when his computer crashed."

Midwifery advocates argue that home births are safer becausethe mother and baby are exposed to fewer people and fewer germs.

In this sentence, the dependent clause "because the mother and baby are exposed to fewer people and fewer germs" is introduced by the subordinating conjunction "because."