Explanation

In this sentence, "He's" is a contraction of "He has", showing present perfect tense.

"He has written a letter" is the full form.

Explanation

A comet grows a tail when it approaches the Sun due to the heat causing the ice to vaporize, releasing gas and dust.

This process forms a glowing coma and tail, which always points away from the Sun due to solar wind.

Explanation

Explanation

Let's solve this problem:

Initially, food is enough for 36 people for 20 days.

Total food = 36 people * 20 days = 720 people-days

When 12 more people come, the total number of people becomes:

36 + 12 = 48

Now, let's find out how many days the food will last for 48 people:

720 people-days / 48 people = 15 days

Explanation

Negative reinforcement strengthens behavior by removing an unpleasant stimulus after the desired response.

It usually follows prior conditioning, encouraging repeated behavior to avoid discomfort.

Explanation

The Concrete Level of cognitive development involves direct interaction with objects and includes attention, discrimination, mental imaging, and memory of attributes.

Recognizing and remembering a red ball fits well with this hands-on, sensory-based stage

Explanation

A treaty is a formal agreement, usually between countries.

Treaty means باضابطہ معاہدہ ، عام طور پر ممالک کے مابین

Explanation

A lever consists of three main parts: Load (the object to be moved), Effort (the force applied), and Fulcrum (the pivot point).

These parts work together to make lifting or moving objects easier.

Explanation

Nerve cells (neurons) generally do not divide after maturity and can live a lifetime.

They are responsible for transmitting signals in the body and are long-lived.

Explanation

Adding the suffix “er” to a verb (teach) forms a noun meaning "one who performs the action."

So, teacher is a noun.