what is the meaning of "the pull through"?

[Lui]

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #92 "Sand Idioms", question 1

The sands of ......... are running out and you'll have to hurry up.

(a) moment
(b) clock
(c) minute
(d) time

English Language Proficiency Tests, Advanced Level

ESL/EFL Test #92 "Sand Idioms", answer 1

The sands of time are running out and you'll have to hurry up.

Correct answer: (d) time
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what is the meaning of the pull through?

Lui

[Mister Micawber]

.
Pull through
.
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Native English teacher at Mister Micawber's