Did you know that there is an exception in forming the past tense form for some Russian verbs which have the infinitive ending in -чь, -ти, -нуть? The suffix л is not used to form the past tense form of such verbs if they are used with singular masculine subjects.
- беречь – Саша берёг (to keep – Sasha kept)
- сохнуть – цветок сох (to dry – the flower was drying)
However, the suffix л is used for the same verbs if they are used with singular feminine and neutral, as well as all plural subjects. For example:
беречь – берегла, берегли.
сохнуть – сохла, сохли.