in Blocktrail.com support open service private key or not
because i can't find about private key in Blocktrail.com
you can see about private key in Blocktrail.com
It's not possible to see the private keys since It's both multi signature and HD wallet , It's however possible to recover your wallet In case something bad happens to the service Itself :
https://blog.blocktrail.com/2015/11/blocktrail-wallet-recovery-tool/They should've gave you a PDF document to download and print when you first made the wallet , that should be used to recover your BTCs .