In 1881, French chemist Camille Faure redesigned the rechargeable lead-acid battery. Faure's design greatly increased the amount of electricity that...

Sentence Structure

In 1881, French chemist Camille Faure redesigned the rechargeable lead-acid battery. Faure's design greatly increased the amount of electricity that the original battery, which the French physicist Gaston Planté [? tense] fifteen years earlier, could hold.

Understanding the Meaning

Let's start from the beginning:

• The first sentence tells us: 'In 1881, French chemist Camille Faure redesigned the rechargeable lead-acid battery.'
  • So in 1881, Faure took an existing battery design and improved it.

Now the second sentence continues:

• 'Faure's design greatly increased the amount of electricity that the original battery... could hold.'
  • Faure's improvement made the original battery design able to store more electricity.

But then we get more information about that original battery:

• 'which the French physicist Gaston Planté ______ fifteen years earlier'
  • This is where we have the blank. Let's look at the choices:

The choices are:

• is inventing, will invent, invents, had invented

So we're deciding what tense to use for when Planté invented the original battery.

To see what works here, let's understand the timing of these events:

• Faure redesigned the battery in 1881
  • This is stated in simple past: "redesigned"
• Planté invented the original battery "fifteen years earlier" than 1881
  • So Planté's invention happened around 1866
  • This is an earlier past event - something that happened before another past event

What do we notice about the time relationship here?

• We have two events, both in the past:
  • First: Planté invented the original battery (earlier past - around 1866)
  • Second: Faure redesigned it (later past - 1881)
• When we're talking about two past events, and one happened before the other:
  • We use a special form for the earlier event
  • We say "had" plus the past form of the verb
• The phrase "fifteen years earlier" is a clear signal
  • It tells us we're talking about something that happened before the main past event

So we need: had invented

This shows the proper sequence: Planté had invented the battery first (earlier past), then Faure redesigned it (later past).

Grammar Concept Applied

Showing the Sequence of Past Events

When you have two events that both happened in the past, and you want to show that one happened before the other, you use different forms:

• Earlier past event: Use "had + past participle" (called past perfect in grammar terms)
• Later past event: Use simple past tense

Example from another context:

• "By the time we arrived at the theater, the movie had already started."
  • Earlier event: the movie started → "had started"
  • Later event: we arrived → "arrived"

In this question:

• Earlier event (around 1866): Planté invented the battery → "had invented"
• Later event (1881): Faure redesigned it → "redesigned"

Signal phrases that often indicate you need past perfect:

• "fifteen years earlier" (as in this question)
• "before that"
• "previously"
• "by the time"
• "already"

These phrases tell you that you're establishing a sequence where one past action came before another past action.