Назовите исследователей Африки. Какова роль каждого из них в изучении материка?

How could you understand that she is lying? May be, he knows it but don`t want to tell us. you could say it to me yesterday! i can`t refuse him - he did too many things for me. may i will come later? can you give me 20 pounds? you should look sharp you may be late. i will do everything that i can for helping you. i can pass exam one more time. may be, he has repeated  yet.