21. Every morning, the fish mongers stood there ______ with the fishermen for fishes.
It was on May 12, 2008 ______ the Wenchuan Earthquake happened.
Mother told me ______ near the river.
His friends ignored his advice, ______ they knew it to be helpful.
I ______ along the road when I saw Peter. So we stopped and had a chat.
Betty will ring me up as soon as she ______ in Beijing.