The phrase "supposed to attach" is correct and can be used in written English.
This phrase is primarily used to indicate that something is expected or intended to be connected with something else. For example, "We were supposed to attach the presentation to the email."
The owner is supposed to attach a repair receipt.
The worst thing about the costume, though, was the Velcro strip on the inside of the headpiece, which was supposed to attach to a cap worn underneath.
The back has one big suction cup (with a sliding lever that increases the suction for an amazingly strong bond), which you're supposed to attach to the airplane video screen on the seat back in front of you.
The amine end of the DGA molecule is supposed to attach onto the ZrP nanoplatelets, similar to other amine molecules for the reaction and intercalation with ZrP platelets.
Is the great certainty of the cogito supposed to attach to the "I think," the "I am," or the "therefore" (i.e., their logical relation)?
Cancer cells are so diverse that certain ones might not bear the antibody to which a molecular label is supposed to attach.
"I thought they were supposed to be attached to a rope".
In the Balls' arrays of photos, clippings and invitations, "anything that was supposed to be attached is becoming unattached," said Karen M. Vincent, Minnetrista's director of collections.
"You're not supposed to get attached, but he's like family," said Ms. McGhee, who, in addition to her teenage sons, has two adult children from an earlier relationship.
In the pure realms of science, they're probably not supposed to get attached at all (theories aren't cats), but scientists are human, too, no matter how sniffy stringent rationalists might get about the issue.
She's not supposed to get attached to the animals that come and go in their Californian yard, any more than she's supposed to learn about evolution or cheek her parents, but that's not an easy rule to follow when you spend every day in the saddle.
