What was a man made cause of the Dust Bowl?
1 point
O
Global warming from the use of fossil fuels
O
The construction of the Hoover Dam shifting dirt
O
Excessive mining in the region
O
The removal of prairie grass for farming

Poor farming choices, for example removing grass along with severe drought

Explanation:

B.   the sentence should read:   as i came in the front door, eddie went out the back door(or something similar to that)

a. this is a correct change in tense.   "the barrier will drop down every time that a train approaches the crossing."   basically this says that "when the train does this, the barrier does "

b. this is incorrect because the sentence starts in the past progressive tense, but ends in the present progressive.

c.   this is also correct.