English Grammar Review
Prepositions and Conjunctions

Subordinating Conjunctions

Conjunctions join things and explain relationships.

Consider the following examples:

(1) Singapore has the world's most competitive economy, and it's a global hub for finance and trade.

(2) Singapore has the world's most competitive economy, so it's a global hub for finance and trade.

(3) Singapore is a global hub for finance and trade because it has the world's most competitive economy.

In sentence (3) we have a subordinating conjunction. It joins the clauses, but it also clearly explains a relationship: "statement2 being true causes statement1 to be true." It indicates a tight connection.

There are many subordinating conjunctions. Some of the most commonly used are:

after . because . if . once

since . though . unless . until

when . where . while

Attributes of subordinating conjunctions

Connection: Subordinating conjunctions provide a tighter connection between clauses than coordinating conjunctions do.

Rohan is responsible for the outline, and Kam will write the first draft.
[loose connection]

If Rohan is responsible for the outline, Kam will write the first draft.
[tight connection]

Placement: A subordinating conjunction may appear at a sentence beginning or between two clauses in a sentence.

After Mr. Tan makes the call, Mrs. Lim reports her results.

Mr. Tan makes the call after Mrs. Lim reports her results.

After Mrs. Lim reports her results, Mr. Tan makes the call.

Mrs. Lim reports her results after Mr. Tan makes the call.

[all placements are acceptable]

Punctuation: When a subordinating conjunction appears between two clauses, it does not require a comma in front of it. See examples above.

The lack of a comma signifies a tight connection:

M if N.
M after N.
M because N.
M unless N.
M when N.

Note1: Remembering when to not use a comma in front of a conjunction requires correctly identifying all the subordinating conjunctions, right? No. Just memorize the coordinating conjunctions (and, but, or, yet, so), for which the mnemonic device A-BOYS can be used.

Note2: Some subordinating conjunctions can also function as prepositions. Examples include after, before, since, and until.

We haven't seen Lee since he led the last meeting.
[conjunction]

We haven't seen Lee since Tuesday.
[preposition]

Lesson: Subordinating Conjunctions
Module: Prepositions and Conjunctions
Course: English Grammar Review