Adverbials are relatively mobile in their positions, they can occur relatively freely in the initial or final position of a sentence. So adverbials become a useful device to highlight a piece of information, as shown:
1a. 孩子们在花园里（positional adv.）像快乐的小鸟似的（manner adv.）跑来跑去。
Háizimen zài huāyuán lǐ xiàng kuàilè de xiǎoniǎo sì de pǎoláipǎoqù.
(The children were running all over the garden like happy birds.)
1b. 像快乐的小鸟似的（manner adv.），孩子们在花园里（positional adv.）跑来跑去。
Xiàng kuàilè de xiǎoniǎo sì deháizimen zài huāyuánlǐ pǎoláipǎoqù.
(Like happy birds, the children were running all over the garden.)
1b’ 孩子们在花园里（positional adv.）跑来跑去，像快乐的小鸟似的（manner adv.）。
Háizimen zài huāyuán lǐ pǎoláipǎoqù, xiàng kuàilè de xiǎoniǎo sì de.
(The children were running all over the garden, like happy birds.)
[1] Loar, J. K. (2011). Chinese syntactic grammar: functional and conceptual principles. New York: Peter Lang.
