Bonnie Buratti of NASA's Jet Propulsion Laboratory ______ data about Saturn's rings collected by the Cassini spacecraft when she made...

Let's begin by understanding the meaning of this sentence. We'll use our understanding of pause points and segment the sentence as shown - understanding and assimilating the meaning of each segment bit by bit!

Sentence Structure

• Bonnie Buratti
• of NASA's Jet Propulsion Laboratory
• [?] data
• about Saturn's rings
• collected by the Cassini spacecraft
• when she made an interesting discovery:
• the tiny moons
• embedded between and within Saturn's rings
• are shaped by the buildup of ring material on the moons' surfaces.

Understanding the Meaning

Let's start reading from the beginning:

• "Bonnie Buratti of NASA's Jet Propulsion Laboratory..."
  • We're being introduced to a scientist who works at NASA.

This is where we have the blank - she does something with "data about Saturn's rings collected by the Cassini spacecraft."

Let's look at the choices:

• studies (present)
• has been studying (present perfect continuous)
• will study (future)
• was studying (past continuous)

So we're deciding what tense to use. To see what works here, let's read the rest of the sentence and understand what it's saying!

The sentence continues: "when she made an interesting discovery"

• "when she made an interesting discovery"
  • "Made" is past tense - this discovery happened in the past
  • The word "when" is connecting two actions

Now let's understand what this structure is telling us:

• The sentence structure is: She [blank - did something with data] WHEN she made a discovery
• This is describing two past actions happening together:
  • One action was ongoing - she was doing something with the data
  • Another action occurred during that time - she made the discovery
• "When" signals that the discovery happened DURING the data work

What do we notice about the time relationship here?

• We have "when she made" - that's simple past tense for a completed action
• The blank describes what was happening AT THAT MOMENT - an action in progress when the discovery occurred
• When we show an action that was in progress in the past while something else happened, we use "was/were + verb-ing"

So we need was studying - this shows she was in the middle of studying the data when the discovery happened.

The rest of the sentence tells us what she discovered:

• "the tiny moons embedded between and within Saturn's rings are shaped by the buildup of ring material on the moons' surfaces"
  • The discovery was about how these tiny moons get their shapes

Grammar Concept Applied

Using Past Continuous to Show Actions in Progress When Something Else Happened

When you're describing two past actions and one was ongoing when the other occurred, you use different verb forms to show this relationship:

• Past continuous (was/were + verb-ing) for the action that was in progress
• Simple past for the action that occurred/interrupted during that time
• "When" often connects these two actions

Pattern:

[Subject] + was/were + [verb-ing] + when + [subject] + [simple past verb]

Examples:

1. In our question:
   • "Bonnie Buratti...was studying data...when she made an interesting discovery"
   • "was studying" = ongoing action in progress
   • "made" = action that occurred during that time
2. Another example:
   • "The researchers were analyzing the samples when they noticed an anomaly"
   • "were analyzing" = ongoing action
   • "noticed" = action that happened during the analyzing
3. Think of it this way:
   • The past continuous sets the scene - describes what was happening
   • The simple past describes the event that occurred in that scene
   • "When" shows the connection between them

This pattern helps create a clear picture of how events unfolded in the past - showing what background activity was happening when a specific moment occurred.