Answer:
2. Luis wrote the problem on the chalkboard though it wasn't clear for the class to understand.
3. Dogs bark as we as protect their owners.
4. The reward was divided equally amongst three who won the contest.
5. Marta expected to meet her friend whom she had invited to the baseball game at the ticket booth.
6.The two storey building built in the 1880's has lost its shingles( I didn't see this word clearly).
Explanation:
We usually use words like because, though , although, as well as to join sentences together they are referred to as coordinating conjunction.
Also we use 'who' or 'whom' which are noun modifiers.
