Explanation

"He wrote a letter yesterday" is the simple past tense expressing the completion of the action of writing in the past. 

Since 'yesterday' is mentioned, we can understand that the letter had been written in the past.

Therefore, we take the simple past form of 'write.'

Explanation

The cat is UNDER the table

In this sentence, the word "under" showcases the location of the cat (subject) with regard to the table (object),

hence under is a preposition.

The words "cat" and "table" are nouns and "under" is used after the subject noun

Explanation

A bird lives in a nest (Relation: Bird: nest)

Similarly, child: house → A child lives in a house

Explanation

Birds have feathers on their body

similarly: cats have fur on their body

Explanation

Carbon-12 (12C) is the most abundant of the two stable isotopes of carbon (carbon-13 being the other), amounting to 98.93% of element carbon on Earth;

its abundance is due to the triple-alpha process by which it is created in stars.

Explanation

He was unfit for the job

وہ اس کام کے لیے نااہل تھا۔

unfit for use means: not suitable or good enough for a particular purpose or activity

Explanation

the finger is to the elbow as the toe is to the knee.

Reason: the finger is the end point of the elbow,

similarly, the toe is the end point of the knee.

Explanation

 A century can only start with a Monday, Wednesday, Friday or Saturday,

so it will end on Sunday, Tuesday, Thursday or Friday.

So the only day which can both start or end a century is FRIDAY.

There are two types of centuries - one that ends with a leap year and one that does not.