Χαίρετε!
I need to write, “Having left town, she went down to the sea.”
I wrote, “λιποῦσα τὸ ἄστυ, κατέβαινε εἰς τὸν θάλλαταν.”
The answer book wrote, "τὸ ἄστυ λιποῦσα εἰς τἠν θάλατταν κατέβη.
The trouble I am having is that the author placed the finite verb in the first exercise in the imperfect, “κελεύσοντος τοῦ στρατηγοῦ πάντες παρὰ τὸν ποταμὸν ἤλαυνον φυλάττομενοι.”
It seems to me that both should either be in the imperfect or both in the aorist. /shrug
It seems to me you don’t understand the difference between imperfect and aorist. The aorist indicates a mere action and, with the indicative, it can only be a past action. The imperfect indicates an incomplete or continuing or attempted action. So κατέβη means that the lady went down and an action was completed. Your κατέβαινε, which is not wrong per se, means that she started to go down, was going down, attempted to go down, depending on the context. Make sure you have clear in your mind the concept of aspect. Mastronarde must devote some space to explain it. Then you should be able to distinguish also ἤλαυνον vs. ἤλασαν.
I thought the first and third sentences were similar in that the soldiers were marching while the woman was driving/walking/running. However she got to the sea.
I think you need to think more carefully about what Bedwere has said about the difference between the aorist and the imperfect.
Look again at unit 16 about the imperfect. In particular p 131 :
"3. Imperfect Indicative. The Greek imperfect indicative refers to action in the past that was incomplete (hence the name, from the Latin for unfinished), in progress, or repeated or customary. It corresponds to the English past progressive (I was sending), verb phrases with used to (I used to send), and in some contexts the English simple past (I sent).
You will find a discussion of the difference between time and aspect on p. 163 unit 20. Note in particular this from p 165:
"3. Aorist-Stem Aspect. The aorist stem conveys an action that is instantaneous and includes conceptually its completion. In the indicative, since the aorist carries no suggestion of duration or of permanent results of the action, it is used to refer to a simple, unique occurrence in the past (for instance, for the statement of historical fact):
οἱ Ἀθηναῖοι τὸν Σωκράτη ἠδίκησαν. …The Athenians wronged Socrates.
ἀπέθανον ἐν τῇ μάχῃ ἑπτὰ ὁπλῖται. …Seven hoplites died in the battle. "
So in the first of your two examples “the army was marching along the river”, we dont know from the sentence whether they completed their journey. All we know is that the author tells us about an uncompleted action in the past, so the tense used has to be imperfect. On the other hand in “she went down to the sea” all we know is that a woman set off for the sea and arrived, ie she went (down) to the sea. This is a completed action in the past. So it is an aorist.
This distinction is of fundamental importance in Greek and unless you grasp the idea of aspect you are going to have a lot of trouble reading Greek in the future. It is worth taking the time to master it.
I presume κελεύσοντος (future) is a typo for κελεύσαντος, aorist. And it’s the aorist that’s needed, not the present.
Plato’s Republic begins κατέβην χθὲς εἰς Πειραιᾶ, ‘Yesterday (χθές) I went down to Piraeus.” The aorist tells us he got there. If he’d set out but never made it, it would be κατέβαινον, imperfect. But it would also be imperfect if he went there every day, not just yesterday.
A tricky thing, aspect. The aorist is “perfective,” the imperfect is “imperfective.” (Aspect is different from tense.) And the present can be either one. Confusing? Hell yeah, and Lukas I wouldn’t worry too much about it until you get your elementary Greek on a firmer footing. But I thought you’d like to see the Plato. There’s a story that Plato experimented with shuffling the words of the opening around till he found the best one. So he too paid attention to word order. 