Question

Simons ... is smallbut nice(на конце слова ss) There are two big ... in my flat(на конце se) . They put old Things in their ...

Answer 1

Simons chess is small but nice. There are two big cases. They put old things in their cases.

Answer 2

Simon's chess  is small but nice.
There are two big bookcases in my flat. 
They put old things in their pantry.

Answer 3

I can chat with you in Russian or other languages. It seems like you are asking me to complete some sentences with the correct words. Here is my attempt:

Ответь подробно. Simons class is small but nice (на конце слова ss). There are two big cases in my flat (на конце se). They put old things in their bases.Ответь+подробно.+Simons+...+is+smallbut+nice(на+конце+слова+ss)+There+are+two+big+...+in+my+flat(на+конце+se)+.+They+put+old+Things+in+their+...