The answer is 'b'. The phrase is mostly used when describibing your frustrations when you can't find something.
I believe the correct answer is sentences 2,5 and 6.
Complex sentences are composed of one independent
clause and at least one dependent clause. The examples from "The Enigma
Machine” which are complex sentences are:
<span>2. </span>For
example, Bletchley Park was crucial in the Battle of the Atlantic, which lasted
six years.
5. This
was provided in a codebook, which was a monthly list of daily keys distributed
to various networks in the German military.
6. Since
the Enigma machine could encrypt text into over 150 trillion possible
combinations, Germans were convinced the codes were not decipherable.
T<span>o say Jeannette Walls had a rough childhood, filled with its fair share of hardships, would be quite the understatement.</span>
