单选题：— I like your new shoes!— Thanks. I had to try on almost a ..

(2013·长沙二模)—The research on the new flu virus vaccine is challenging and demanding.Who do you think can do the job?—________ my students have a try?A．May B．MustC．Will D．Shall

—It's no easy task to catch a ticket on a website that receives 1 billion clicks daily.—I can't agree with you more. There ________ be errors for every single step.A．should B．mustC．can D．will

She ______ have attended that meeting, for she was doing paperwork in the office then.A．shouldn’tB．mustn’tC．wouldn’tD．couldn’t

—Whom did you ________ the packet at the post office?—Jack.There________ masses of work for him to do, but he managed to finish the work as required.[ ]A. have fetched; was B. have fetch; wereC. have to fetch; wereD. have fetch; was

_____ volleyball is her main focus, she's also great at basketball.A. SinceB. Once C. UnlessD. While