I often have conversations with John over ______ telephone, while I keep in touch with Tom by ______ letter.
I could _______ by the way she walked that her knee was still bothering her.
My parents ______ me to go to the theatre with my classmates but I didn’t want to.
Sea water ______ many minerals, salt ______.
----How do you like the book?----It’s quite different from ______ I read last month.
I will carry out the plan _____ there is much difficulty ahead.