Premium economy shell seats on Japan Airlines. Premium economy is a travel class offered on some airlines. Positioning in price, comfort, and amenities, this travel class is leveled between economy class and business class. In 1991, EVA Air was the first to introduce Evergreen Class and had since become the first airline to offer this class of service in the world.
This sentence has two independent clauses. They are connected by and with a comma before it. The and and the comma are correct. However, adding a comma after thus is not correct because it is an adverb; the comma after it is not necessary. If thus is used as a conjunctive adverb (without and), a semi-colon and a comma are necessary.
1 Commas should be placed before and after a non-essential element in the middle of a sentence. 2  use a comma after an opening clause, word, or phrase. 3  use a comma to follow conventions of naming, citing sources, presenting addresses, dates, etc. Commas should be placed before and after a non-essential element in the middle of a sentence. 2  use a comma after an opening clause, word, or phrase. 3  use a comma to follow conventions of naming, citing sources, presenting addresses, dates, etc.