Question 17-20 are based on the following passage. Fill in the blanks with the best transitional expression. I’ve had a lot of trouble with my car leaking oil lately. First, there’s a pool of oil two thirds of the way up on both sides of the driveway. There’s ____17____ pool in the garage where I park the car. ____18____ I cleaned up the oil, the next day it’s back again. ____19____, I took the car to the garage to have the oil changed and the leak stopped. ____20____, the problem was more difficult than I’d expected. The rear main bearing seal was leaking, but to replace it, the engine would have to be pulled. I couldn’t afford that, so I had to wait and save up some money.