1.Would you please(not open)the window?It’s too cold.

1.Would you please not open(not open)the window? It’s too cold.
解析：would you please (not) do sth. 请（不要）做某事,好吗?
2.Let’s not go(not go)out at the moment ,It’s raining heavily.
解析：let sb.(not) do sth. 让某人（不）做某事
3.He got up late and didn't have (not have ) breakfast this morning.
解析：didn't have 和got up是并列的谓语动词,形式应该相同.

1.Would you please(not open)the window? It’s too cold. 用原形
2.Let’s (not go)out at the moment ,It’s raining heavily。用原形
3.He got up late and (didn‘t have ) breakfast this morning. 加助动词

don't open
not go
didn't have