Please note: the word 'that' may be omitted in English, for example:
We expect the shop is open today
but must be shown in Welsh:
Rydyn ni'n disgwyl bod y siop ar agor heddiw
Example (2) is a compound sentence in which the second clause provides additional information about a person or thing which was introduced in the first clase. For example:
Did you see the man who was driving the car?
first clause second clause
We put up the mirror which we bought in the sale.
first clause second clause
If the person or thing in the first clause does something in the second clause, then the parts of the sentence should be linked with 'sydd'.
first clause action--> second clause
For example:
Dyma'r teulu sydd yn symud i mewn i'r tŷ.
This is the family who are moving into the house.
The family mentioned in the first clause is carrying out the action of 'moving into the house' (i.e. they are the subject) in the second clause.
Rydyn ni'n siarad â'r dyn sydd yn torri'r lawnt.
We are speaking to the man who is cutting the lawn.
The man mentioned in the first clause is carrying out the action of 'cutting the lawn' (i.e. he is the subject) in the second clause.
If the person or thing in the first clause is having some action carried out on it by the second clause, then the parts of the sentence should be linked with 'y mae'.
first clause <--action second clause
For example:
Dyma'r tŷ y mae'r teulu'n ei brynu.
This is the house that the family is buying.
The house mentioned in the first clause has the action of 'being bought' carried out on it in the second clause.
Canmolodd yr adroddiad y mae'r rheolwr wedi'i ysgrifennu.
He praised the report that the manager has written.
The report mentioned in the first clause has the action of 'being written by the manager' carried out on it in the second clause.