Question

Can somebody please help me I don't understand​

Answer 1

Answer: Roosevelt was intent on building a canal across Panama that would shorten that trip by around 5000 miles.

OR

Roosevelt wanted to build a canal across Panama that would shorten the trip by 5000 miles.

OR-- assuming the numbers in the prompt are incorrect-- and should have referred to lines 4 and 5:

He wanted to build a canal that would benefit communication, trade and defense.

Explanation:  The relative pronoun, that, relates canal in the main clause and replaces the canal in the second sentence so it can be inserted into the first sentence.

It may seem confusing, but the sentences have to be reworked a bit more in this example-- by changing the verb forms along with creating the relative clause.

The sentences in lines 4 and 5 are much easier to combine using that because the repeated canal is so close to the sentences that introduces the idea of building the canal.

Answer 2

Its simple all you have to do is put the words in order