Neil Armstrong and Buzz Aldrin ________ (collect) some moon dust samples before they ________ (return) to Earth.
had collected - returned collected - had returned collected - returned has collected - returnedMôn học
Chủ đề / Chương
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Chủ đề
Neil Armstrong and Buzz Aldrin ________ (collect) some moon dust samples before they ________ (return) to Earth.
had collected - returned collected - had returned collected - returned has collected - returned
