1. They don't allow___the building until they finish___it. a.entering/renovating b. to enter /to renovate c. entering/having renovated d. to enter/renovate 2. I'd prefer___for the next bus rather than travel on a crowded one because I have difficulty___up for long. a.waiting/to stand b. to wait/standing c. wait/in standing d. to be waiting/stand 3. Will you stop___with your fingers? I'm trying ___on my work. a. tapping/concentrating b. to tap/to concentrating c. having tapped/concentrated d. tapping/to concentrate 4. Obsessive people can't help___a particular activity over and over again. a.having been doing b. having done c.doing d.to do