The railroads help transfer people and goods across the United States lot faster than on horse. Also helped with mailing.
The correct answer is was working.
You need to use past continuous tense (was working) to denote that an action which was being processed for a period of time has now been interrupted. So, Penelope was working on her homework for a prolonged period of time, and then the doorbell rang and interrupted her.
The disadvantages of keeping money in home depends on how much cash, but there are many disadvantages. You are earning any return on that money so you are losing spending power, the longer you keep it at home. You could physically lose it.
