That makes it difficult to identify the cause of the United States' poor performance.
This makes it difficult to identify the majority of specimens collected in the field.
However, heterogeneity in differentiation in vitro makes it difficult to identify mDA neurons in culture or in vivo following transplantation.
This makes it difficult to identify a set of related authors or to group authors by subjects in retrieval systems.
However, the fragmented nature of the findings makes it difficult to identify how or why criticism impacts on OCD.
However, heterogeneity in differentiation in vitro makes it difficult to identify mDA neurons in culture or in vivo following transplantation.
Unfortunately, speaking about health spending at that level of aggregation and abstraction makes it difficult to identify the precise steps necessary to reduce spending.
"These youngsters have no ID cards, so it makes it difficult to identify them," said Zhang Xiang, a spokesman for the Guangdong Labor Bureau.
Often, negative impacts are highly interconnected or only become visible after considerable time, which makes it difficult to identify cause-and-effect relations.
The fault in one process variable readily affects the other variables which makes it difficult to identify the fault variable precisely.
This makes it difficult to identify elder abuse from the outside looking in.
