How do I love thee by Elizabeth Barret Browning

Here are the answers to your questions:

4.2.1 This poem is a Petrarchan sonnet. It consists of 14 lines written in iambic pentameter, divided into an octave (eight lines) and a sestet (six lines).

4.2.2 The word "thee" in modern English is you.

4.2.3 The speaker's beloved (her husband, Robert Browning) is addressed as "thee" in this poem.

4.2.4 When the speaker says, "I love thee to the depth and breadth and height," she means that her love is immeasurable and all-encompassing, reaching every dimension and aspect of her being.

4.2.5
4.2.5.1 "Sun" symbolises grand, public, or divine love, while "candle-light" symbolises intimate, personal, or earthly love.
4.2.5.2 The literal meaning of "sun" is the natural light of day, and "candle-light" is the artificial light of a candle at night.

4.2.6
4.2.6.1 The speaker will use a sincere, humble, or devoted tone in this line.
4.2.6.2 The speaker would use this tone to convey that her love is unselfish and genuine, not seeking recognition or reward.

4.2.7 The correct answer is B. Hyperbole.

4.2.8 "Lost saints" refers to the speaker's past ideals, beliefs, or perhaps even religious devotion that she has either lost or replaced with her profound love for her beloved.