根据对话内容，从对话后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。
----- Can you help me?
----- Sure, what’s the problem?
----- ____81___.
----- Well, how about San Francisco? We went there last year and had a great time.
-----82
-----Well, there is Golden Gate Bridge of course, and Golden Gate Park. It’s a really big park. You can go for long walks or take a rest in the Japanese Tea Garden. It’s beautiful there.
-----83
----- There is also a place called Fisherman’s Wharf. That’s really popular with tourists. There are lots of shops, cafes and restaurants. And from there you can go on a boat trip to Alcatraz. You know, it’s a small but very beautiful island.
-----84
----- No, you can’t stay on the island; there aren’t any hotels. You can only go for the day. I think I’ve still got a book about San Francisco. I can lend it to you.
-----85
What can you do there?
Oh, great! What a great place to stay in!
What an idea! What is the best time to go there?
I can’t decide where to go for the holiday-----any ideas?
Thanks a lot. San Francisco, here I come!
Hmm, that sounds good.
How can I go there?
可知，R与导体两端电压U成正比，与通过导体的电流I成反比