"Lengthwise' and "securely" are the adverbs. Adverbs modify the verb, and tell how something is done.
We is not an adverb.
I fastened my seatbelt for the ride.
Weight is measured in kilos, liquid is measured in litres and sound is measured in decibels.
The germ measured a few micrometers.
I measured my water bottle in newtons.
You measured the frame lengthwise and then fastened it securely. There are two adverbs in this sentence - lengthwise (modifying measured) and securely (modifying fastened). All other words are not adverbs.
We is not an adverb.
Please make sure that your seat belt is securely fastened.
I fastened my seatbelt for the ride.
She fastened her seatbelt.We have fastened him to the altar, signal the dragon to accept the offering.
securely
Yes, the word securely is an adverb.An example sentence is "he securely tied the boat to the harbour".
I fastened the clasp of her new necklace at the back of her neck.
Before the storm, I tethered the boat securely to the dock.
Example sentence - We will make sure our boat is securely docked for the night before we leave.
all the inmates are securely locked in the asylum
The fuselage is the main body of an aircraft, designed to accommodate passengers, cargo, and the flight crew.