I saw Jack sitting 　　　　　(在……旁边) Jim talking.
I don’t understand the meaning of this　　　　　(符号).
My sister got the answer to the 　　　　　 (谜语) very quickly.
Many people are against 　　　　　(做实验) on animals.
He gave me a 　　　　　(恰当的) example, so I understood it easily.