Câu 1: `→` The explanation was too difficult I to understand

Câu 2: `→` I went tobed early because for me to understand it

*Cấu trúc: 

S + be + so + adj + that + S + can't/coudln't + V

`⇒` S + be + too + adj +`\text(to)_(\text(infi))`

$\text{@su}$

Câu `1`: The explanation was so difficult that I couldn’t understand it

`→` The explanation was too difficult for me to understand it.

`⇒` S + tobe + so + adj + that + S + V

     = S + tobe + too adj + for sb + to V

Câu `2`: I felt very tired so I went to bed early

`→` I went to bed early because I felt very tired.

hoặc I went to bed early because of being tired.

`⇒` clause 1 + so + clause 2 = clause 2 + because + clause 1 = clause 2 + because of + N/V-ing

$\text{#BTS}$