今晚有空吗?
Are you free tonight? *free“空闲的”。
Are you free tonight? (今晚有空吗?)
Yes. Why? (有空，干嘛?)
Do you have plans tonight? (今天晚上有事吗?)
Are you available tonight?
Are you busy tonight? (今天晚上忙吗?)
今晚你能和我约会吗?
Do you want to go out with me tonight? *go out并不一定就是“约会”，但是如果go out的后面直接跟with me的话，就一定是“约会”了。