The lessons provided by Duolingo are designed to increase in difficulty as the user            .

A. variety

B. difference

C. similarity

D. diversity

A. To explain how technology has changed the banking transactions.

B. To explain how to advertise through the internet.

C. To explain how to do business online.

D. To explain how technology has facilitated business and trade.

A. Alaska is melting!

B. Life in Alaska

C. Alaska’s glaciers

D. An overview on Alaska

A. were attempted

B. attempted

C. have attempted

D. had attempted

A. Our wedding had to be postponed until September.

B. Not until September did we have to put off our wedding.

C. Our wedding until September had to be postponed.

D. It was not until September that our wedding had to be put off.

A. introduced

B. completed

C. commenced

D. launched