我找不到钥匙了，肯定放在门边的桌上了。
I can't find my keys — I must have placed them on the table by the door.
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must英 /mʌst/|美 /mʌst/
placed英 /pleɪst/|美 /pleɪst/
解释
must + have + 过去分词 placed，对自己过去的行为做肯定推断。对自己用 must have 时常带有轻微不确定感，但表达高度可能性。
I can't find my keys — I must have placed them on the table by the door.
must + have + 过去分词 placed，对自己过去的行为做肯定推断。对自己用 must have 时常带有轻微不确定感，但表达高度可能性。