"Comma splice"

• L'anglais n'emploie pas de virgule pour séparer des phrases grammaticalement séparées (= avec un autre sujet et/ou verbe). La faute est connue sous le nom de "comma splice". Dans ce cas, il faut (selon le sens) employer un point, un point virgule ou deux points:

The temperature became milder, spring had started.
=> The temperature became milder: spring had started.
La température devint plus douce: le printemps avait débuté.

Hemingway was a great writer, he had a way with words.
=> Hemingway was a great writer.  He had a way with words.
Hemingway était un grand écrivain.  Il savait comment se servir des mots.

This chapter has a lot of difficult information in it, you should start studying right away.
=> This chapter has a lot of difficult information in it: you should start studying it right away.
Ce chapitre contient des tas d'informations difficiles: tu devrais commencer à l'étudier tout de suite.

Mr. Brook has sent his four children to college, however, he has had to work day and night to earn the money for it.
=> Mr. Brook has sent his four children to college; however, he has had to work day and night to earn the money for it.
Monsieur Brook a envoyé ses quatre enfants à l'université; or, il a dû travailler nuit et jour pour gagner l'argent nécessaire.

This computer doesn't make sense to me, it came without a manual. 
=> This computer doesn't make sense to me. It came without a manual.
Je ne comprends rien à cet ordinateur. Il a été livré sans mode d'emploi.

Coordination