Plastic bags are provided for our convenience but they have also __________ the pollution of the environment.
________ the course very difficult, she decided to move to a lower level.
The sun began to rise in the sky, ________ the mountain in golden light.
When I was little, my mother used to sit by my bed, ________ me stories till I fell asleep.
Sitting at the corner of the meeting room, he looked sad because there were so many problems ________.
By the age of two, Heidi could count to 40, draw pictures of people, and read books ________ for sevenyearolds.