Enter Into

[katieq]

How do I use 'enter' and 'enter into' for these sentences:

1. The project entered a critical phase.
2. The project entered into a critical phase.

3. They entered an agreement with a company.
4. They entered into an agreement with a company.

[riquecohen]

How do I use 'enter' and 'enter into' for these sentences:

1. The project entered a critical phase.
2. The project entered into a critical phase.

3. They entered an agreement with a company.
4. They entered into an agreement with a company.

Welcome to the forum, katieq.
In yiur examples, I would say that #1 and #4 are correct.
In #1, "enter" means to begin a new phase in a process. In #4, "enter into" signifies joining in or participating in something.
The word "enter" can be used in many different ways. You can go to OneLook Dictionary Search and find many nuances.

[SoothingDave]

I like either 1 or 2, but only 4.