Straight forward, just explain to you the job nature and requirements. No question that make you difficult, but they require you to do a simple english test and logical test.
I applied in-person. The process took 2 weeks. I interviewed at Certis (Singapore) in June 2017
Interview
Asked a few questions, if your weight is good and you have the basic education levels, eg
1. N levels/O levels
2. Nitec/Higher Nitec
3. Diploma/Private Diploma
4. Private Degree
Diploma onwards - SGT
Nitec - CPL