Read the following text and use modifiers as directed in the blank spaces:

Trees, (a) ______ (use an apositive), are essential for maintaining eco-system. Without trees, the balance of eco-system will be (b) ______ (post modify the verb) lost. Trees provide us with (c) _____ (pre-modify the noun) elements without which we cannot live on this earth. It is a matter of (d) ______ (pre-modify the noun) concern that we are felling trees (e) ______ (post modify the verb). As a dire consequence, the global temperature is rising (f) ______ (post modify the verb). The existence of flora and fauna is at an (g) ________ (use a pre-modifier) risk. Polar ice caps are melting and (h) ______ (use a noun adjective) level is rising. (i) ______ (use a present participle phrase), we can avoid such a catastrophe. If we want to keep our (j) _______ (use a noun adjective) earth safe and sound, we have to plant trees and protect our forests.

The original sentence contains a common grammatical error known as a dangling participle or dangling modifier. A participial phrase or other introductory phrase is said to "dangle" when the noun it describes is not clearly stated in the sentence, or when it modifies a word other than the one intended.

In the sentence "Walking down the road, a bus hit Mr. Khan," the participial phrase "Walking down the road" incorrectly seems to modify "a bus." Logically, it is Mr. Khan who was walking down the road, not the bus.

To correct a dangling modifier, you can:

    
• Change the main clause so its subject is the noun that the modifier describes. (e.g., "Walking down the road, Mr. Khan was hit by a bus.")
    
• Rewrite the participial phrase as a subordinate clause with its own subject. (e.g., "While Mr. Khan was walking down the road, a bus hit him.")

The corrected sentence "Walking down the road, Mr. Khan was hit by a bus" makes it clear that Mr. Khan is the one performing the action of walking, thereby resolving the ambiguity and correcting the dangling modifier.

The original sentence suffers from a dangling participle. A participial phrase, such as "Seeing the advancing army," is meant to modify the subject of the main clause. In the original sentence, "all valuables" is the subject of the main clause, but it is illogical for "valuables" to "see" an army.

To correct this, the subject of the main clause must be the logical agent performing the action described by the participle. By introducing "the people" as the subject, the sentence becomes grammatically correct and logically coherent, as it is the people who saw the army and then hid the valuables. This ensures that the participial phrase correctly modifies the intended subject.