This question tests your understanding of tenses and conditional sentences. The structure "As soon as..." describes a future action and its immediate consequence.

Step 1: Analyze the first blank
The phrase "As soon as he ____ to Copenhagen" refers to a future event. In such time clauses (introduced by words like when, as soon as, before, after), we use the present simple tense to talk about the future, not "will". Therefore, the correct form is "gets".

Step 2: Analyze the second blank
The second part of the sentence, "he ____ us a letter", describes the action that will happen immediately after the first action is completed. Since the entire situation is set in the future, the second verb must be in the future simple tense ("will send").

Final Answer: The most appropriate words to fill in the blanks are gets and will send.
The complete sentence is: As soon as he gets to Copenhagen he will send us a letter.

Related Topics & Formulae

Time Clauses (Future Reference):
When the main clause is in the future tense, the time clause (introduced by when, as soon as, until, before, after) is in the present tense.

Formula:
$\text{As soon as + Present Simple,}\text{Future Simple}$