再问一个 I didn·t know what was happening.同义句 I didn·t know what was —— ——.

再问一个 I didn·t know what was happening.同义句 I didn·t know what was —— ——.
再问一个 I didn·t know what was happening.同义句 I didn·t know what was —— ——.

再问一个 I didn·t know what was happening.同义句 I didn·t know what was —— ——.
I didn·t know what was happening.同义句 I didn·t know what was taking place/coming up

taking place
happen 和 take place 都有“发生”的意思

going on