This question tests your understanding of past habits and abilities in English grammar. Let's analyze the sentence structure and meaning:

Context: The sentence describes a childhood habit (taking a flashlight to bed) and the purpose behind it (reading comics secretly).

Step 1: Analyzing the first blank
We need an expression that describes a repeated past action (a habit from childhood). The options are:

• "was used to taking" - This describes being accustomed to something, not performing a repeated action
• "used to take" - This correctly expresses a past habit
• "would take" - This can also express past habits but is less common for single events
• "would have taken" - This is conditional, not for describing past habits

Step 2: Analyzing the second blank
We need a verb that expresses past ability (the capability to read secretly). The options are:

• "could" - Expresses general past ability
• "can" - Present tense, incorrect for past context
• "was able to" - Also expresses past ability, but often for specific occasions

Step 3: Finding the correct combination
"Used to take" perfectly describes the childhood habit, and "could" correctly expresses the general ability to read secretly. The other combinations either use wrong tenses or inappropriate expressions for past habits.

Final Answer: The correct option is "Used to take / could"

Related Grammar Concepts

Used to vs. Would: Both can describe past habits, but "used to" is more common for states and repeated actions, while "would" typically describes repeated actions with specific time references.

Could vs. Was able to: Both express past ability, but "could" is used for general abilities while "was able to" often emphasizes success in specific situations.

Key Formulas/Rules

Past Habits:
Subject + used to + base verb (for past habits and states)
Subject + would + base verb (for repeated past actions only)

Past Ability:
Subject + could + base verb (general ability)
Subject + was/were able to + base verb (specific ability or achievement)