2. They paint their house in blue. their house is painted in blue 

3. They built the Eiffel Tower between 1887 and 1889. Eiffel tower was built  between 1887 and 1889

4. They stole my wallet at the airport yesterday. my wallet was stolen  at the airport yesterday

5. Lan often washes dishes. dishes are often washed by lan 

6. We should use computers for studying online. computers should be used for online by us