赤毛のアン2章12

She was sitting there waiting for something or
somebody and, since sitting and waiting was the
only thing to do just then, she sat and waited
with all her might and main.

with all one's might and main:一生懸命に

その子はそこに座って何かを、誰かを待っていた。そ
の時は座って待つしかなかったので、一生懸命座って
待っていたのだ。

赤毛のアン2章11

Had he looked he could hardly have failed to notice
the tense rigidity and expectation of her attitude
and expression.

never fail to:必ず～する
tense:張り詰めた
rigidity:硬さ
expression:表情

見ていたら、その子の態度や表情から期待と緊張がきっと
見て取れていただろう。

Had he looked = If he had looked の仮定法

赤毛のアン2章10

Matthew, barely noting that it WAS a girl, sidled
past her as quickly as possible without looking
at her.

barely:辛うじて～する
sidle:横に歩く,

コソコソ歩く 女の子だとはほとんど気付きもせずに、
マシューはその方向を見ることもなく急ぎ足でこそっ
と通り過ぎた。