Is a comma used after conjunctive adverb or transitional expression?

Yes, a comma is usually used after a conjunctive adverb or transitional expression when it comes at the beginning of an independent clause.

Here's why:

* Conjunctive adverbs (like *however*, *therefore*, *moreover*, *furthermore*, *consequently*, *nevertheless*, *indeed*, etc.) and transitional expressions (like *on the other hand*, *in addition*, *for example*, *as a result*, etc.) connect independent clauses.

* Placing a comma after them helps to clarify the separation between the clauses and makes the writing easier to read.

Example:

* Incorrect: We have to finish this project by Friday. However it might be difficult with the holiday weekend.

* Correct: We have to finish this project by Friday. However, it might be difficult with the holiday weekend.

Exceptions:

* Short clauses: If the clauses are very short, a comma may not be necessary.

* Emphasis: Sometimes, you might choose to omit the comma for emphasis, especially when the conjunctive adverb or transitional expression is used to create a strong connection between the clauses.

Remember:

* These are general guidelines. There are always exceptions depending on the specific context and style of writing.

* Always double-check your writing to ensure the comma is placed correctly and helps to improve clarity.