Use WHICH as a complex sentence Use ALTHOUGH as a complex sentence
Use EVEN THOUGH as a complex sentence
Use THAT as a complex sentence
Use UNLESS as a complex sentence

please do it in order

this may help? a complex sentence is a sentence that contains a subordinate clause or clauses! hope that helps!

have a great day!

onto a large boat, and mark the water level that the boat sinks to. then, take the elephant out and put a bunch of marked weights onto the boat until it reaches the same water level. add up the masses of the weights to get the weight of the elephant.