注）shall : 必ずやる （強い決意）
注）by means of ～ : ～を使って、～を用いて
注）Cunning Trap : 巧妙な罠
have to は「～すべきことを持っている」という外的な要因で必要に迫られているというニュアンスです。
注）That's just it ：まさしくそれだ
Piglet said that this was a very good Trap, but supposing it were raining already?
Pooh rubbed his nose again, and said that he hadn't thought of that.
And then he brightened up, and said that, if it were raining already, the Heffalump would be looking at the sky wondering if it would clear up,
and so he wouldn't see the Very Deep Pit until he was half-way down.... When it would be too late.
Pooh was very proud when he heard this,
and he felt that the Heffalump was as good as caught already,
but there was just one other thing which had to be thought about, and it was this.
Where should they dig the Very Deep Pit?
Piglet said that the best place would be somewhere where a Heffalump was, just before he fell into it, only about a foot farther on.
注）see 目的～ing : ～が～しているのを見る
注）suspect : （きっとそうだと）疑う
注）happened to ～ : たまたま～する
注）not as ～ as ～ ：～ほど～ない
注）hardly ever : なかなか～しない
注）get caught ：捕まる