"Masomo yamekuwa mawe"
Translation:The lessons have become difficult
Also: 'The lessons have been difficult'. Use of the perfect tense with '-kuwa' is complicated, since ‘being’ is not an action which can easily be seen as having been ‘completed’ (and the present tense ni would normally be used to describe a state). However, if a state of being has helped you to your current situation, use of -me- it might be appropriate: 'nimekuwa mwanafunzi' – I have been a student (until recently). '-Kuwa' also has an extended meaning of ‘to become/get’, which can be used with the perfect, and even the present, tense: Amekuwa mzee – he/she has become old; 'Mnakuwa wanene!' – you are (all) getting (becoming) fat!