Perfect & Continuous Aspect

Gap-Filling Exercise

Complete the sentences with the Perfect or Continuous form of the verb in brackets, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. Note that you will lose points if you ask for hints!
1. Recently, scientists (make) several important discoveries about how the brain works, but they still (need) to do more research.
2. She always (know) when her brother (lie), because he would turn bright red.
3. I asleep (fall) when a thought (occur) to me.
4. The criminal (not understand) that someone (follow) her for months before she (be) arrested.
5. The researcher's office is quiet because he (not like) a lot of distractions when he (think).
6. The writer (sell) her first novel a decade ago, and currently she (work) on her fifth.