1.

1. It was doubtless his own fault.
    那肯定是他自己的过错。

2. Doubtless he was the strongest.
    他无疑是最强有力的。

3. He will doubtless arrive by the next train.
    无疑他会坐下趟火车到的。

1. doubtless的反义词

1. 无疑的：doubting 怀疑 | doubtless 无疑的 | douce 沉着的

2. 无疑的,很可能的：doubtful 怀疑的,可疑的 | doubtless 无疑的,很可能的 | down 下,向下,顺...而下

3. 无疑地：doubtful 可疑的 | doubtless 无疑地 | dough 生□□

4. doubtless

4. 很可能：defenseless 无防御的 | doubtless 很可能 | downless 无软毛的

1. 很可能地;几乎肯定地
    If you say that something is doubtless the case, you mean that you think it is probably or almost certainly the case.

公共查询·英语单词大全

    e.g. He will doubtless try and persuade his colleagues to change their minds...
           他很可能会试图说服同事们改变主意。
    e.g. Doubtless he was justified in some of his criticism of the media...
           他对媒体的一些批评性言论无疑是合乎情理的。

1. without doubt
    certainly

    e.g. it''s undoubtedly very beautiful

    Synonym: undoubtedlydoubtlessly