Miller: Every Friday after work, a group from the office goes out for Happy Hour. I was wondering if you'd like to join us this evening.
Linda: I'd be delighted. Thank you.
Miller: Happy Hour starts at 5, we'll leave the office a little early. Say 4:50?
Linda: That sounds fine with me. Where exactly do you go?
Miller: There is a bar and grill across the street that an old friend recommended to me. The food there is great and the atmosphere is very relaxed and informal.
Linda: Great! I'm looking forward to it.
請問：
1. 從這段會話可以很明顯知道Miller和Linda是現在正在對話中，而且談的不是過去的事情。在"I was wondering if you'd like to join us this evening."這句中， 為什麼wonder要用過去進行式was wondering表示？
2. 可不可以用現在進行式is wondering表示？若不行的話，請問為什麼？
更新1:
修正問題2的內容。 2. 可不可以用現在進行式am wondering表示？若不行的話，請問為什麼？
