Selecting objects which are fully inside the marquee or lasso

well, yes, the drawings from AutoCad are not so easy to work in Illustrator.

What I tried to do (it was quite quick):

1. As the lines are in 2 appearances, solid and dashed, I used Select > Same > Appearance command and grouped the selected objects. This way I isolated the lines from all other parts of artwork. You can also temporarily turn Off the group's visibility to see better other objects.

2. Without the contours, it's easy to select the needed filled objects. Now it was enough to just click on the top light-blue elements with Shift keeping. In other cases you can use lasso or Select > Same > /the needed property/ command. So I moved the selected objects to the new layer ("Silhouette").

3. Activate Isolated mode for contours (double-click on any line in the group).

4. This step is not so nise because all parts of the outline are divided by intersection points. It's no way to select them together and not catch others with the same properties. So I suggest to start from the outer part which must be moved to Silhouette layer. Select them (I clicked at the each dash with Shift), cut and paste-in-place on the needed layer.

5. This will create an empty area around the inner elements and you can select them by lasso easily.

the result: https://drive.google.com/open?id=1hEg7zwMGWZxyZCkBQNrzX7MOG2TAL-rS

I hope this workaround can help to do the job a bit faster 🙂

While there isn't an option to only select objects completely inside a selection, there are a bunch of different ways to make selections --like by various attributes or other tools. Can you describe a little more about the scenario, and maybe we can find a different technique to help?

no way. Illustrator always selects the whole objects which are at least touched (Selection tool or Group Selection tool) or the points which are inside the drawn area (Direct Selection tool, Lasso tool). Modificators just switch the tools or allow to add/remove something to selection.