placenta (noun) membrane: covering layer
Detalii: tissue is a collection of cells that form a thin but tough structure and each type of tissue has a special function; a membrane is a thin layer of tissue
Sinonime: be cautious, be concerned, be on guard, be solicitous, be wary, have a care, mind one's p's and q's, take care,
tend, toe the line,
trouble,
watch, watch one's step, watch out