I can hardly believe my eyes. Is that you, Lucy- Yes. It has been almost 20 years______ we were together.

______he was exercising at the park yesterday morning, he found a purse under the tree.

Hey, boys and girls! Stop ____. I have somethinginteresting to tell you.

The security guard(保安) kept the students ________ order while they were walking into the museum.

下列句子中，没有语病的一句是（ ）