Tomwasupsetbecausemostofhisfriends

問題詳情：

Tom was upset because most of his friends ________ when he __________ at the party. He just saw some of them.

       A. had left; had arrived     B. had left; arrived    C. left; arrived    D. left; had left

【回答】

B

知識點：動詞時態

題型：選擇題