1.   Where externalities and jointness are perceived, exchanges have begun to cooperate.

2.   Also that day, the exchange began twice-weekly trading, on Sundays and Wednesdays.

3.   A spokesman for the Chicago Board Options Exchange had no comment on whether the exchange had begun an investigation of the trading.

4.   Afterwards, an exchange of presents began.

5.   In short order, the existing exchanges began to show more interest in competition.

6.   Last month, the exchange began using an electronic order-driven trading system that matches buy and sell orders electronically.

7.   That exchange began an unlikely story in the delicate match between organ donor and recipient that experts say is becoming more and more common.

8.   The electronic exchange began operations in June.

9.   The exchange began with Ito asking the former football star how he felt.

10.   The exchange of gunfire began after one of the passengers exited the vehicle brandishing a weapon, shooting one soldier in the chest and the other in the arm.