C2: Verbs: Progressive Tense: Use the auxiliary verb “to be” + a present participle to form progressive verb tenses correctly. See Writing for Success Section 5.5 pp. 200-203 or the following: http://www.cws.illinois.edu/workshop/writers/perfectforms/
Progressive tense shows action in progress in the past, present, or future:
The car was swerving from lane to lane.
The brothers were waving at everyone they passed.
Frederick is serving a dish from every continent.
The graduates are lining up behind the auditorium.
The Martians will be landing in South Dakota.
Maurice will be camping nearby.