Explanation

Perennial Canals flow throughout the year

Thus referred to as perennial canals.

They draw water from perennial rivers or from artificial reservoirs

which sustain a high water level on the upstream side.

Explanation

Franklin D. Roosevelt served as U.S. President from 1933 to 1945

He led the country through most of World War II.

During World War II, two atomic bombs over the Japanese cities 

• First Bomb, the Little Boy type of bomb was dropped in Hiroshima on 6 August 1945 
• Second bomb, the Fat Man type of bomb was dropped on Nagasaki on August 9, 1945

The Second World War was a global war

That started in 1939 and ended in 1945

Additional information:

Woodrow Wilson is the President during World War I

He served as the 28th president of the United States from 1913 to 1921.

Explanation

• The main window in a computer spreadsheet is called a workbook
• while 
• The title bar in MS Excel displays the name of the  worksheet
• **
• In Excel, when we create a new document, we always select a blank workbook, as you already have done in the previous chapter.
• When this blank workbook opens up, an interface you see is called a workbook window.
  

Explanation

At the primary level, teaching in the mother tongue helps children understand better and feel more comfortable.

Teachers using the child's native language can connect better.

It often show more patience in communication and learning.

Explanation

Laser technology is used in optical disks (like CDs and DVDs).

It allowing for precise data storage and retrieval.

Explanation

"The committee is meeting tomorrow."
"Committee" is a collective noun and is treated as singular in American English, so it takes "is".

Explanation

Cells are the basic building blocks of all plants and animals.

It forming the fundamental structure and function of living organisms.

Explanation

The correct use of tenses is: "Your mother had been waiting for you when you went to your friend's house."

This sentence correctly uses the past perfect continuous tense to describe an action that was ongoing in the past before another past action.

Explanation

The function of "Save As" in Microsoft Office is to ask the file name and store data in the desired location.

It allows you to save a copy of the document with a new name or in a different location, without overwriting the original file.

Explanation

The sentence structure "had been + verb (-ing)" indicates the Past Perfect Continuous Tense.

This tense is used to show an action that started in the past and continued for a certain duration before another past event.