Our classroom is very clean. Do you know who＿＿cleaned it﹖

I phoned you at six yesterday afternoon, but nobody answered.—-I _______ a walk with my parents near the river.

We won’t go shopping if it ________ this afternoon.

I called Nina several times, but she didn’t answer. — Of course, she ____________ London for a visit.

Pollution is ______bad ______many rivers are full of chemicals and kill sea creatures.