Откройте скобки. Используйте прошлые простые или настоящие совершенные времена.
1. He (to give) his first lecture in banking in 2002. He (to become) a brilliant lecturer since.

2. We first (to observe) this effect in 2008. We (to make) good progress in studying it since.

3. I (to come) to work at this university in 2006. I (to publish) eight papers since.

4. Some years ago my friend (to read) a book on the history of economics. He (to be) interested in studying economics since.