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.